explain xkcd - User contributions [en]

1181: PGP

2013-03-05T15:23:47Z

70.48.8.178:

{{comic
| number = 1181
| date = March 4, 2013
| title = PGP
| image = pgp.png
| titletext = If you want to be extra safe, check that there's a big block of jumbled characters at the bottom.
}}

==Explanation==
{{w|Pretty Good Privacy|PGP}} (Pretty Good Privacy) is a program which can be used to encrypt and/or sign data, including messages sent as emails. Encrypting means encoding data in a way that requires a known key to decrypt and read; signing means that there is a code included in the data which can be used to verify both that the data is unaltered and to verify the true sender.

In the case of the email in this comic, it has only been signed; not encrypted (hence, the top of the first line of text can be seen and is legible in normal English). This is more common than encryption, as reading an encrytpted message would require the recipient to already be a PGP user. In fact, the use of PGP even to sign email messages is so rare that most people have probably never seen a signed message. Because a signed email is so rare, and because it is already legible and unencrypted, [[Randall]] is making the observation that few users actually bother to use the signature to verify the authenticity of the sender using the PGP signature, and make the assumption that the fact that there IS a signature is good enough evidence that the message is authentic. He may also be implying that because PGP signatures are so rare and probably ignored by most recipients, he would not expect anyone to even bother creating a false PGP signature; therefore the mere existance of a PGP header will indicate authenticity. The title text extends the joke by suggesting you confirm there's a bunch of random characters in the footer (this is the actual key that PGP generates which can be used to verify the authenticity of the email. Again, Randall is saying that the existance of the block is itself evidence of authenticity.

==Transcript==
:How to use PGP to verify that an email is authentic:
:Look for this text at the top
:[In mail header, light grey.] Reply
:-----BEGIN PGP SIGNED MESSAGE-----
:[in mail message, light grey]
:HASH: SHA256
:Hey,
:First of all, thanks for taking care of

:[After mail message]
:If it's there, the email is probably fine

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]

1181: PGP

2013-03-05T15:20:37Z

70.48.8.178: With all respect, This talks a lot about privacy, security, and PGP's workings, but I don't think that explains this comic; I was very confused when I read the explanation; I think it more clearly explains the comic now.

{{comic
| number = 1181
| date = March 4, 2013
| title = PGP
| image = pgp.png
| titletext = If you want to be extra safe, check that there's a big block of jumbled characters at the bottom.
}}

==Explanation==
{{w|Pretty Good Privacy|PGP}} (Pretty Good Privacy) is a program which can be used to encrypt and/or sign data, including messages sent as emails. Encrypting means encoding data in a way that requires a known key to decrypt and read; signing means that there is a code included in the data which can be used to verify both that the data is unaltered and to verify the true sender.

In the case of the email in this comic, it has only been signed; not encrypted (hence, the top of the first line of text can be seen and is legible in normal English). This is more common than encryption, as reading an encrytpted message would require the recipient to already be a PGP user. In fact, the use of PGP even to sign email messages is so rare that most people have probably never seen a signed message. Because a signed email is so rare, and because it is already legible and unencrypted, [[Randall]] is making the observation that few users actually bother to use the signature to verify the authenticity of the sender using the PGP signature, and make the assumption that the fact that there IS a signature is good enough evidence that the message is authentic. He may also be implying that because PGP signatures are so rare and probably ignored by most recipients, he would not expect anyone to even bother creating a false PGP signature; therefore the mere existance of a PGP signature will indicate authenticity.

==Transcript==
:How to use PGP to verify that an email is authentic:
:Look for this text at the top
:[In mail header, light grey.] Reply
:-----BEGIN PGP SIGNED MESSAGE-----
:[in mail message, light grey]
:HASH: SHA256
:Hey,
:First of all, thanks for taking care of

:[After mail message]
:If it's there, the email is probably fine

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]

1177: Time Robot

2013-02-22T20:08:39Z

70.48.8.178:

{{comic
| number = 1177
| date = February 22, 2013
| title = Time Robot
| image = time robot.png
| titletext = NO FATE BUT THE NARRATIVES WE IMPOSE ON LIFE'S RANDOM CHAOS TO DISTRACT OURSELVES FROM OUR EXISTENTIAL PLIGHT
}}

==Explanation==
The comic starts with a scene from a 1984 science fiction action film ''{{w|The Terminator}}'', in which a killing robot (played by {{w|Arnold Schwarzenneger}}) is sent back in time to kill Sarah Connor, the main female protagonist of the movie, and a human, Kyle Reese, also travels back in time to protect her (and he acquires a {{w|sawed-off shotgun}} which Cueball holds in the strip).

However, in the following panels, Cueball explains that, even if he succeeds protecting Megan from the killing robot, we all are hunted by an unstoppable enemy trying to kill us – time. He goes on to point to the similarities between the time and a Terminator. The clock visible in the third panel features a red light in the place of a 3-hour marker, which is a reference to {{w|Terminator (character concept)#Physical characteristics|glowing red eyes}} of a Terminator.

In the final panel, “come with me if you want to live” is a [http://terminator.wikia.com/wiki/Come_with_me_if_you_want_to_live. famous phrase from the movie], but in this case, amended with the facts about the inevitability of eventual death.

Also, the title text is a play on a quote from ''The Terminator'', where Sarah Connor starts to believe that “[http://terminator.wikia.com/wiki/There%27s_no_fate_but_what_we_make_for_ourselves. There's no fate but what we make for ourselves.]”. It is also a reference to the character “{{w|Death (Discworld)|Death}}” in {{w|Terry Pratchett}}’s ''{{w|Discworld}}'' novels. In the Discworld novels, Death’s voice is always depicted in <span style="font-variant:small-caps">small caps</span> and he is often caught making sometimes bizarre philosophical statements about life and death.

==Transcript==
:[Cueball runs towards Megan with shotgun in hand.]
:Cueball: I'm from the future!
:Cueball: You're being stalked by an unstoppable robotic assassin!

:[Close up of Cueball's head.]
:Cueball: Of course, in a sense, we're ''all'' being stalked by an unstoppable robot.
:Cueball: A robot called ''time''.

:[Cueball looking at a clock.]
:Cueball: I see it in the mirror. I see wrinkles, grey hairs.
:Cueball: I hear its metallic footsteps in the relentless rhythm of the ticking clock.

:[Cueball reaches out to Megan.]
:Cueball: Anyway, uhh - come with me if you want to live for a while.
:Cueball: You'll still die eventually.
:Cueball: We all will.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with color]]

1174: App

2013-02-15T14:48:38Z

70.48.8.178: /* Explanation */

{{comic
| number = 1174
| date = February 15, 2013
| title = App
| image = app.png
| titletext = If I click 'no', I've probably given up on everything, so don't bother taking me to the page I was trying to go to. Just drop me on the homepage. Thanks.
}}

==Explanation==
Some web sites have a {{w|mobile app}} designed for use on mobile devices such as smartphones and tablets. In theory this is because the main website will be more difficult to navigate on the small screen of a moble, or some features won't work. In practice, this alternative is frequently worse than simply viewing the standard web page, for reasons offered in the comic:

*You cannot zoom or change the text size in most of these apps, a feature available on mobile browsers.
*The app is often of poor quality and is incomplete, lacks part of the content, or lacks features available on the standard web site.

The comic offers a brutally honest version of such a promotional popup. Alternatively to an app, some sites have a mobile version which is still an HTML-based website - just one that has been designed for mobile. These mobile versions (denoted by a domain begining with "m." instead of "www.") often have the same issues as above, or worse, because the sites do not have the benefit of the programability of an app.

Compounding the frustration is that some sites aggressively promote their app/mobile version with a popup message that repeates the suggestion on every visit to the site, and as the title text notes, if you reject the popup, you end up on the site's homepage, rather than the subpage you may have been trying to reach via a web search. A similar effect (where the mobile version will only load the site's main page) is described in more detail in [[869: Server Attention Span|comic 869]].

==Transcript==
:[A popup window on top of a webpage displayed in a smartphone browser.]
:Want to visit an incomplete version of our website where you '''can’t zoom'''?
:'''Download our app!'''
:[OK] [No, but ask me again every time]

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]

1174: App

2013-02-15T14:47:22Z

70.48.8.178:

{{comic
| number = 1174
| date = February 15, 2013
| title = App
| image = app.png
| titletext = If I click 'no', I've probably given up on everything, so don't bother taking me to the page I was trying to go to. Just drop me on the homepage. Thanks.
}}

==Explanation==
Some web sites have a {{w|mobile app}} designed for use on mobile devices such as smartphones and tablets. In theory this is because the main website will be more difficult to navigate on the small screen of a moble, or some features won't work. In practice, this alternative is frequently worse than simply viewing the standard web page, for reasons offered in the comic:

*You cannot zoom or change the text size in most of these apps, a feature available on mobile browsers.
*The app is often of poor quality and is incomplete, lacks part of the content, or lacks features available on the standard web site.

The comic offers a brutally honest version of such a promotional popup. Alternatively to an app, some sites have a mobile version which is still an HTML-based website - just one that has been designed for mobile. These mobile versions (denoted by a domain begining with "m." instead of "www.") often have the same issues as above, or worse, because the sites do not have the benefit of the programability of an app.

Compounding the frustration is that some sites aggressively promote their app/mobile version with a popup message that repeates the suggestion on every visit to the site, and as the title text notes, if you reject the popup, you end up on the site's homepage, rather than the subpage you may have been trying to reach via a web search. This effect described in more detail in [[869: Server Attention Span|comic 869]].

==Transcript==
:[A popup window on top of a webpage displayed in a smartphone browser.]
:Want to visit an incomplete version of our website where you '''can’t zoom'''?
:'''Download our app!'''
:[OK] [No, but ask me again every time]

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]

1173: Steroids

2013-02-14T19:31:48Z

70.48.8.178: /* Explanation */

{{comic
| number = 1173
| date = February 13, 2013
| title = Steroids
| image = steroids.png
| titletext = A human is a system for converting dust billions of years ago into dust billions of years from now via a roundabout process which involves checking email a lot.
}}

==Explanation==
This comic is about steroid usage to enhance one's performance; it is likely inspired by {{w|Lance Armstrong}}'s recent confession to blood doping in a televised interview with {{w|Oprah Winfrey}} (although Armstrong's confessions did not itself include {{w|anabolic steroid}} use; "steroids" is a common catch-all phrase often misused to reference other forms of doping).

The comic states that humans are essentially made up of chemicals, and they need other chemicals to survive -- for example, food, water and air are made up of chemicals. Humans also have a propensity for competition to find out which person is the fastest and strongest.

This comic is making the point that the criteria about which chemicals (steroids) humans may or may not take in to be considered the strongest or fastest is an artificial criteria. This is demonstrated by [[Megan]] explaining the whole concept to a non-humanoid entity; when framed the way Megan frames it, the explanation sounds rather trivial and silly.

The title text changes the perspective again by suggesting that humanity itself is trivial in the grand scheme of things and that really all we are is a "transition" state between old dust and new dust, with a bunch of emailing in between.

The comic was published on {{w|Ash Wednesday}} (Western liturgical start of Lent). The dust to dust reference calls to mind the charge, "Remember man that thou art dust and unto dust you shall return," which is traditionally spoken by priests as they place ashes on the foreheads of observers on Ash Wednesday.

==Transcript==
[Megan is talking to something which has a black spot in the center and six rays in a star- shaped form.]
:Something: Explain to me this "steroid scandal."
:Megan: Well, uh... We humans are sacks of chemicals which stay alive by finding other chemicals and putting them inside us.
:Megan: We hold contests to see which humans are fastest and strongest.
:Megan: But some humans eat chemicals that make them ''too'' fast and strong.
:Megan: And they '''win contests'''!
:Something: That does sound bad.
:Megan: It's awful!
{{comic discussion}}
[[Category:Biology]]
[[Category:Comics featuring Megan]]

1173: Steroids

2013-02-14T16:27:08Z

70.48.8.178: /* Explanation */

{{comic
| number = 1173
| date = February 13, 2013
| title = Steroids
| image = steroids.png
| titletext = A human is a system for converting dust billions of years ago into dust billions of years from now via a roundabout process which involves checking email a lot.
}}

==Explanation==
This comic is about steroid usage to enhance one's performance; it is likely inspired by {{w|Lance Armstrong}}'s recent confession to blood doping in a televised interview with {{w|Oprah Winfrey}} (although Armstrong's confessions did not itself include {{w|anabolic steroid}} use; "steroids" is a common catch-all phrase often misused to reference other forms of doping).

The comic states that humans are essentially made up of chemicals, and they need other chemicals to survive -- for example, food, water and air are made up of chemicals. Humans also have a propensity for competition to find out which person is the fastest and strongest. But there also is an artificial boundary about which chemicals humans may or may not take in to be the strongest or fastest. The comic is also about how silly the arguments on steroid use would appear if we were trying to explain it to a non-organic entity. The title text changes the perspective again suggesting that it's all ultimately transitory as from dust to dust can be taken quite literally.

The comic was also published on {{w|Ash Wednesday}} (Western liturgical start of Lent). The dust to dust reference calls to mind the charge, "Remember man that thou art dust and unto dust you shall return," which is traditionally spoken by priests as they place ashes on the foreheads of observers on Ash Wednesday.

==Transcript==
[Megan is talking to something which has a black spot in the center and six rays in a star- shaped form.]
:Something: Explain to me this "steroid scandal."
:Megan: Well, uh... We humans are sacks of chemicals which stay alive by finding other chemicals and putting them inside us.
:Megan: We hold contests to see which humans are fastest and strongest.
:Megan: But some humans eat chemicals that make them ''too'' fast and strong.
:Megan: And they '''win contests'''!
:Something: That does sound bad.
:Megan: It's awful!
{{comic discussion}}
[[Category:Biology]]
[[Category:Comics featuring Megan]]

1173: Steroids

2013-02-14T16:26:52Z

70.48.8.178:

{{comic
| number = 1173
| date = February 13, 2013
| title = Steroids
| image = steroids.png
| titletext = A human is a system for converting dust billions of years ago into dust billions of years from now via a roundabout process which involves checking email a lot.
}}

==Explanation==
This comic is about steroid usage to enhance one's performance; it is likely inspired by {{w|Lance Armstrong}}'s recent confession to blood doping in a televised interview with {{w|Oprah Winfrey}} (although Armstrong's confessions did not itself include {{w|anabolic steroid}} use; "steroids" is a common catch-all phrase often misused to reference other forms of doping).

The comic states that humans are essentially made up of chemicals, and they need other chemicals to survive -- for example, food, water and air are made up of chemicals. Humans also have a need for competition to find out which person is the fastest and strongest. But there also is an artificial boundary about which chemicals humans may or may not take in to be the strongest or fastest. The comic is also about how silly the arguments on steroid use would appear if we were trying to explain it to a non-organic entity. The title text changes the perspective again suggesting that it's all ultimately transitory as from dust to dust can be taken quite literally.

The comic was also published on {{w|Ash Wednesday}} (Western liturgical start of Lent). The dust to dust reference calls to mind the charge, "Remember man that thou art dust and unto dust you shall return," which is traditionally spoken by priests as they place ashes on the foreheads of observers on Ash Wednesday.

==Transcript==
[Megan is talking to something which has a black spot in the center and six rays in a star- shaped form.]
:Something: Explain to me this "steroid scandal."
:Megan: Well, uh... We humans are sacks of chemicals which stay alive by finding other chemicals and putting them inside us.
:Megan: We hold contests to see which humans are fastest and strongest.
:Megan: But some humans eat chemicals that make them ''too'' fast and strong.
:Megan: And they '''win contests'''!
:Something: That does sound bad.
:Megan: It's awful!
{{comic discussion}}
[[Category:Biology]]
[[Category:Comics featuring Megan]]

1170: Bridge

2013-02-06T14:40:55Z

70.48.8.178:

{{comic
| number = 1170
| date = February 6, 2013
| title = Bridge
| image = bridge.png
| titletext = And it says a lot about you that when your friends jump off a bridge en masse, your first thought is apparently 'my friends are all foolish and I won't be like them' and not 'are my friends ok?'.
}}

==Explanation==
"If all your friends jumped off a bridge, would you jump too?" is a common phrase, meant to challenge someone who indicates their desire to do something is that all their friends are doing the same thing. It is meant to cause the person to consider whether the fact their friends are doing something, alone, means something is a good idea. The form of the statement with "your friends" replaced by another group or a specific individual is also used.

The comic points out a logical fallacy with the statement, in that while many of the person's friends are actually doing what the subject intends to do, it is extremely unlikely that all of the subject's friends would suddenly jump off a bridge, precisely because it is a bad idea. [[Cueball]] responds by assuming that if all of his friends jumped off a bridge, there must have been some extreme circumstance that made it logical to do so; for example, that the bridge is on fire.

==Transcript==
:[A youthful Cueball talking to an unseen parent.]
:Parent: No, you can't go.
:Cueball: But all my friends —
:Parent: If all your friends jumped off a bridge, would you jump too?
:Cueball: Oh, jeez. Probably.

:Parent: What!? Why!?
:Cueball: Because all my friends did.
:Cueball: Think about it — which scenario is more likely:

:Cueball: Every single person I know, many of them levelheaded and afraid of heights, abruptly went crazy at exactly the same time...
:Cueball: ...or the bridge is on fire?

:Parent: ...I, uh...hmm.
:Cueball: Imagine reading this on CNN: "''Many fled their vehicles and jumped from the bridge. Those who stayed behind...''"
:Cueball: Is something ''good'' about to happen to those people?
:Parent: Maybe they'll find cookies?
:Cueball: OK, ''you'' stay. I'm jumping.

{{comic discussion}}
[[Category:Comics featuring Cueball]]

1163: Debugger

2013-01-21T14:21:33Z

70.48.8.178:

{{comic
| number = 1163
| date = January 21, 2013
| title = Debugger
| image = debugger.png
| titletext = It can take a site a while to figure out that there's a problem with their 'report a bug' form.
}}

==Explanation==
[[Cueball]] mentions to [[Megan]] that he can't understand how his mind works, the same mind he uses to understand how things work, and he's not sure if this is a problem. In other words, if he can't understand how his mind works, then how can he tell that it does in fact work and that his perception of reality if accurate. Ordinarily he would use his mind to figure it out, but if his mind really doesn't work, then he'll probably never determine that his mind doesn't work. Understandably, he's a little unsure of how he should feel about this.

The title text alludes to the problem that if a website's "report a bug" page is buggy or broken to such a degree that it prevents the actual reporting of a bug, specifically that the "report a bug" page is buggy, then it can take time before the website's administrators realises, if they do at all, as unless they test it themselves, the site's administration are relying on users to use the page to report the problem. Which the users can't. This is somewhat analagous to the "brain" dilemma in the main comic, in that they ponder problems occuring in the the normal method of determining that there is a problem.

==Transcript==
:Cueball: I don't understand how my brain works.
:Cueball: But my brain is what I rely on to understand how things work.
:Megan: Is that a problem?
:Cueball: I'm not sure how to tell.

{{comic discussion}}
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Programming]]
[[Category:Philosophy]]