xkcd is a webcomic created by Randall Munroe. The comics tagline describes it as "a webcomic of romance, sarcasm, math, and language." It is widely read and has been recognized in such mainstream media as The Guardian and The New York Times.

The subject matter of the comic varies, including statements on life and love (some love strips are simply art with poetry), and mathematical (Mathematical joke) or scientific (science) in-jokes. Some strips feature simple humor or pop-culture references. Although it has a cast of stick figures, the comic occasionally features landscapes, intricate mathematical patterns such as fractals (for example, strip #17 "What If" shows an Apollonian gasket), or imitations of the style of other cartoonists (as during "Parody Week").

The comic is available under the Creative Commons Attribution-NonCommercial 2.5 License. New comics are added three times a week, on Mondays, Wednesdays, and Fridays at midnight North American Eastern Time (Eastern Time Zone), although on five occasions so far they have been updated every weekday: Parody Week, the "Choices" series, the "1337 (Leet)" series, the "Secretary" series, and the "The Race" series.