What is RSS?
RSS is a type of document that can be used for creating syndicated or subscription content. An RSS file is linked via a website but is opened by RSS Reader softwares. RSS Readers can read the document and interpret the simple information contained within it. The information might be a summary of a website (or the entire text), or perhaps information about an audio or video available for download.
The RSS Reader software displays this information in a nicely formatted way and often provides images, full links to the original website, or links to the audio or video to download. This means you can browse quickly through the information in your RSS Reader and decide which topics you wish to explore in more detail by clicking on the links to the original webpage. Making audio available in this way is sometimes referred to as a Podcast.
Syndication and Subscription
You can use RSS Readers to 'subscribe' to RSS documents. This means you use configure the RSS Reader to (automatically) periodically check an RSS file and notify you of changes and updates. RSS files used like this are often referred to as an RSS Feed or just as a feed. So it is said you use RSS Readers to subscribe to a feed. Content that is distributed this way is often referred to as "syndicated content".
It is important to note that there are many uses for RSS documents, and there are also many softwares that can interpret them in useful ways. There are online RSS Readers which enable you to keep a list of different feeds and read then online. Some online services allow you to include RSS feeds in your own blog or website. This means you can have updated syndicated content within your own website without having to manually find and enter that content yourself. Podcatchers are a type of RSS Reader that you use to subscribe to Podcasts. This term isn't in such wide use and this type of functionality is usually managed by player softwares like iTunes or Rhythmbox.
Also catching on is the use of RSS to syndicate material published in PDF. This is a type of 'bookcast' - an ugly term, but it effectively communicates that publishing is experimenting with this type of content distribution. Making video available with this process is sometimes a vodcast - another ugly name, it is short for "video-on-demand-cast" which is also kind of clumsy.
If there is a feed available you will usually come across it via your web browser. You might see one off these icons somewhere on the page:
Thanks to http://www.rssboard.org for permission to use the above image. As you can see, there a lot of different icons that tell you there is a feed linked from the webpage, but thankfully things are settling down a little and you should be seeing more of this icon :
The above icon is called the universal feed icon, and may appear on webpages (but a lot smaller!) that have a feed available. Clicking on the icon should enable you to subscribe to the feed using your favorite RSS Reader (also referred to as agregators, or feed readers) or, in the case of a Podcast, you can subscribe using your favorite media player (not all of them support this functionality however).
What Does an RSS file Look Like?
When we speak of an RSS file it is really the content of an ordinary text file we are referring to. RSS is the set of rules that dictate how to write a RSS document. If you follow the rules correctly your file can be referred to as a valid RSS file. There are softwares and websites that you can use to check if a RSS file is valid.
You write a RSS file using a text file editor, on Windows this might be NotePad, on MacOSX it might be TextEdit, on Ubuntu or other varieties of Linux you have a wide variety of text editors including Text Editor, Gedit, vim etc.
If you are not used to looking at computer code the structure of an RSS file will look quite odd. Here is a sample:
<?xml version="1.0"?> <RSS version="2.0"> <CHANNEL> <TITLE>FLOSS Manuals</TITLE> <DESCRIPTION>At FLOSS Manuals you can find all the free manuals you could ever want!</DESCRIPTION> <LINK>http://www.flossmanuals.net</LINK> <ITEM> <TITLE>Quote of the day</TITLE> <DESCRIPTION>Free as in Media</DESCRIPTION> <LINK>
</LINK> </ITEM> </CHANNEL> </RSS>
The above is the content of a ficticious RSS feed. If you were to copy the above example and put it online then it would indeed be a feed you could subscribe to, though not a very useful or interesting one.
If you know a little about HTML then you might think it looks a little familiar. Actually RSS rules are derived from another set of rules known as XML, and some versions of HTML also conform to these rules. A simplification of how XML and RSS relate is to consider XML the set of rules governing the structural layout and syntax of the file, while RSS is the set of rules that defines what information can be included and where.