xkcd is a webcomic created by Randall Munroe. The comic's tagline describes it as "a webcomic of romance, sarcasm, math, and language." Also some webcomics about IT may frequently appear on it. For example, the following one-- People who know Unix will understand it easily.In fact, xkcd is a Geek culture, many comics inside this site can only understood by some specified group of people.The comic began in September 2005 when Munroe decided to scan doodles from his school notebooks and put them on his webpage. Eventually the comic was changed into a stand-alone web...