RSS (Really Simple Syndication) allows content publishers to syndicate updates on their websites or blogs. RSS uses XML files called feeds that contain either the full text or a summary with a link to the full content. RSS readers and aggregators allow users to subscribe to these feeds and view updates in a single location. Popular free RSS readers for Windows include Feed Demon, SharpReader, and Mozilla Thunderbird. Web services like Google Reader, MyYahoo, and Bloglines also provide RSS feed aggregation online.