Tags

A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

RSS (an acronym for 'Really Simple Syndication') is an XML-based file format for providing well-defined syndicated content to "feed readers."
about the quarterly creative commons data dumps of all public data in the Stack Exchange network Q&A sites.
a set of tags that can be marked by a user. The questions that have favorite tags will be highlighted, and can be monitored using Tag Sets.