Flatulence is the presence of a mixture of gases known as flatus in the digestive tract of mammals expelled from the rectum. It is more commonly known as 'farting', 'passing gas', 'breaking wind', 'cutting the cheese', or 'passing wind' (UK).

Flatus is expelled under pressure through the anus, whereby, as a result of the voluntary or involuntary tensing of the anal sphincter, the rapid evacuation of gases from the lower intestine occurs. Depending upon the relative state of the sphincter (relaxed/tense) and the positions of the buttocks, this often results in an audible crackling or trumpeting sound, but gas can also be passed quietly. The olfactory components of flatulence include skatole, indole, and sulfurous compounds.
Professional farter
Borborygmus
Vaginal flatulence
The Gas We Pass
Fart lighting
Franklin, Benjamin (2003). in Japikse, Carl (Ed.): Fart Proudly, (Reprint), Frog Ltd/Blue Snake. ISBN 1-58394-079-0. 
Dawson, Jim (1999). Who Cut the Cheese?: A Cultural History of the Fart. Ten Speed Press. ISBN 1-58008-011-1. 
Dawson, Jim (2006). Blame it on the Dog: A Modern History of the Fart. Ten Speed Press. ISBN 1-58008-751-5. 
D. von Schmausen. Official Rules, New World Odor International Freestyle Farting Championship. LULU. 
The Farting Survey (fartsurvey.com) - a comprehensive, worldwide survey about farts and farting.
The Merck Manual of Diagnosis and Therapy, Gas
Facts on Farts
Dictionary of Fart Slang
The Great Fart Survey (simple statistical analysis of flatulence in youths) produced by Australian Broadcasting Corporation youth website, Rollercoaster)
Flatulence Treatment
Fart Sounds - frequently updated flog (fart+blog) dealing with all aspects of flatulence.