What is RSS feed?

RSS or Rich Site Summary is a form of feed, which allows the users to access updates to online digital content in a technical, standardized and compatible format. These feeds allow the users to track the trajectory of many different websites in a single feed aggregator that collects similar information and makes it available for smooth access. The feed aggregator will self- check the RSS feed for fresh content, allowing the content to be passed from website to website or from the website to the user. This automatic passage of content is termed as web syndication. Websites generally use RSS feeds to publish constantly updated information of all file formats such as text, datasheet, audio, and video. An RSS document includes full or précised texts like a publishing company and the author's name.

A standard XML file extension ensures that it is compatible with many other diversified programs. RSS feeds also benefit its users as it constantly updates its users of the new content in their favorite websites or a news aggregate from more than one sites. Subscribing to a websites RSS eliminates the need for the user to check the website for new content. Rather, their browser frequently monitors the website and keeps the user informed of any updates. The web browser can also be set up to automatically download the fresh data for the user.

RSS feed data is made available to its users using a software called the feed aggregator or news aggregator. This web application can be built-in into a website be installed on a desktop computer or a cell phone device. Users can subscribe to the feeds either by incorporating the feed's URI into the reader or by clicking the browser's feed icon. The RSS reader, hence, checks the user's feeds frequently for new information and will automatically download it, if that setting is enabled. The reader also provides a user interface.
A demo RSS feed could look like this:

<?xml version="1.0" encoding="UTF-8" ?>
<rss version="2.0">
 <title>RSS Title</title>
 <description>This is an example of an RSS feed</description>
 <lastBuildDate>Mon, 06 Sep 2010 00:01:00 +0000 </lastBuildDate>
 <pubDate>Sun, 06 Sep 2009 16:20:00 +0000</pubDate>

  <title>Example entry</title>
  <description>Here is some text containing an interesting description.</description>
  <guid isPermaLink="true">7bd204c6-1655-4c27-aeee-53f933c5395f</guid>
  <pubDate>Sun, 06 Sep 2009 16:20:00 +0000</pubDate>


The Atom feed

The Atom feed was proposed and developed as an alternative to RSS feed. Ben Trott, a propounder of the new format Atom, believed that RSS feed had limitations like the lack of on-going innovation and its requisiteness to stay compatible to its previous designs and that there were advantages of a fresh design. 
In June 2003, Sam Ruby set up a wiki to discuss what is needed to make "a well-formed log entry". People started using the wiki to discuss a new format of the syndicate to remove the shortcomings of RSS. It also became understood that the new format could form the basis of a better replacement for blog editing protocols.
The project aimed to develop a format that:
•    Is 100% vendor neutral
•    Can be implemented by everybody
•    Thoroughly specified.
In short order, a road map was built. The efforts quickly attracted over 150 supporters, including Glenn Otis Brown of Creative Commons, David Sifry of Technorati, Jason Shellen of Blogger, Mena Trott of Six Apart, Brad Fitzpatrick of LiveJournal, Jeremy Zawodny of Yahoo, Timothy Appnel of the O'Reilly Network,  and Lawrence Lessig. Other notables supporters of  Atom included Tim Bray, Aaron Swartz, Joi Ito, Mark Pilgrim, and Jack Park. Dave Winer also tentatively supported the new endeavor. 

Atom 1.0 and its standardization:
In 2004, discussions began about moving the project to develop a new feed format to a standards body such as World Wide Web Consortium (WWWC) and the Internet Engineering Task Force (IETF). The group eventually chose the latter and the Atompub working group was formally set up in the month of June 2004. This gave the project a standardization that it needed. The Atompub working group is co-led by Tim Bray and Paul Hoffman. Initial development was primarily focused on syndication format.
The Atom Syndication Format (ASF) was issued as the Proposed Standard in IETF RFC 4287 in the last month of 2005. Mark Nottingham and Robert Sayre were the co-editors. This document is known as atompub-format in IETF's standard terminology. The Atom Publishing Protocol (APP) was issued as the Proposed Standard in IETF RFC 5023 two years later in the month of October 2007. 

Propounders of the new format formed the IETF Atom Publishing Format and Protocol Workgroup. But despite the emergence of Atom feed as an IETF Proposed Standard and the decision by major tech giants like Google to use and support Atom feed, the usage of the previous and RSS formats has continued. Various reasons can be cited in this regard:
•    RSS 2.0 ability to support enclosures led to the development of podcasting, a process of downloading a digital recording from the internet into a device. While many such applications, support the usage of Atom 1.0, RSS 2.0 still remains the preferred format. 
•    Many sites choose to publish their content in a single format. Many tech giants and media companies still prefer the usage of RSS feed 2.0.
•    News articles regarding news aggregator feeds have increased the usage of the term "RSS" to refer to any of the variants of the RSS format like RSS 2.0, RSS 1.0 and also the Atom feed format.