Learn in the textbookDomain Names, DNS, and How the Web Works
DefinitionRSS is a data format that describes a site's updates in a set form, with items such as titles, summaries, and dates.
ExplanationThe data each site publishes is called a feed (フィード) and is based on XML. Register the sites you want to follow in an RSS reader (RSS リーダ), and it gathers their feeds into a list of new articles. You learn about updates without opening each site in turn.
AnalogyLike a newspaper's list of headlines: instead of full text, you get headlines and short blurbs in a fixed layout, and you read only the stories that interest you in the paper itself.
Memory hookOne expansion is Really Simple Syndication. The S for syndication (distribution) reminds you it is a format for distributing content.