chess.com/robots.txt

Well someone has a sense of humor.

Ha!

How did you find that?

robots.txt is the webpage all websites use to communicate with web-bots (in theory-- in practice, mean robots do not respect this), such as googlebot, which updates Google's servers. The whole 

User-agent: * 

Disallow: /admin* 

Disallow: /login_and_go.html* 

Disallow: /echess/download_pgn.html*

Stuff disallows bots from trying to achive pages on chess.com that start with admin, login_and_go, or echess/download_pgn. I imagine this is because these are either a) sensitive material, or b) is expensive for the server to compute (logging in and generating pgn takes awhile for a server to do).

As to why I checked? IDK. It's the "hacker instinct". :P

So what was the humorous part? I didn't catch that... May be due to my not-very-extensive knowledge on the subject.

It's the text afterwords, that has nothing to do with anything... in reference to the fact that the page is always called "robots.txt", they added in a reference to Isaac Asimov's laws of robotics as part of what I assume is a joke.