RSS is a family of web feed formats. The initials "RSS" are variously used to refer to the following standards:

- Really Simple Syndication (RSS 2.0)

- Rich Site Summary (RSS 0.91, RSS 1.0)

- RDF Site Summary (RSS 0.9 and 1.0)

- RSS formats are specified in XML (a generic specification for data formats). RSS delivers its information as an XML file called an "RSS feed", "webfeed", "RSS stream", or "RSS channel".

Programs known as feed readers or aggregators can check a list of feeds on behalf of a user and display any updated articles that they find. It is common to find web feeds on major websites and many smaller ones. Some websites let people choose between RSS or Atom formatted web feeds; others offer only RSS or only Atom.

RSS-aware programs are available for various operating systems. Client-side readers and aggregators are typically constructed as standalone programs or extensions to existing programs such as web browsers and Email readers.

For the rest of the Wikipedia entry on the above term, go here.

Below is a 90s video tutorial explaining what is RSS.