The Basics
An RSS reader is also called a feed reader, rss feed aggregator or aggregator. Such software uses web feeds in order to access content from news sites and other sources like blogs, pods, vlogs, and other websites. RSS readers act like automated content fetchers. When a user subscribes to an RSS feed the reader will automatically get all updates instead of the user having to visit various websites. So if a user collects news from 3 websites, entertainment items from 3 other websites, personal visits to blogs or vlogs from 10 websites, then the RSS reader can be configured so that it will automatically get updated content from those websites instead of the user having to visit 16 individual websites without even knowing if there is anything new to see. Since the user can also select what part of the news section should be included in the RSS feed configuration, the aggregator delivers the most customized content.

Feed and RSS Reader (Push vs. Pull)
The user can specify when to check for updates, every hour or every day, or any other time period as is suitable. Based on this specification the reader will fetch updated content from configured websites. In order for the reader to work the user must first go to the websites and subscribe to the provided feeds. This creates a relationship between feed and reader much like the one between mail server and email client or NNTP server and news reader, except for one critical difference. Email delivery is known as “push” content. This sort of content does not leave much freedom to the user, if you have an email address you will receive email. RSS readers work on a “pull” principle. This means that every subscriber is pulling information from an RSS feed rather than the feed pushing that information to the reader. Users can easily unsubscribe from an RSS feed with minimum propagation time.

Note: KickRSS does not currently allow users when to check for updates. Instead, the KickRSS backengine runs scripts that check for new content every few minutes (always pulling) so that the content you view online is fresh and up to date.

Many popular websites like Google and Yahoo! are making increasing use of aggregators. Other applications that are using aggregators or have aggregator features built into them include web browsers, email clients, and iTunes (podcast aggregator). Mobile phones and video recorders that can handle the XML programming language can also make use of aggregators.

Keywords
Aggregators are convenient because they can gather content from a lot of different sources and display them through a single web browser like interface. This can sometimes create problems as the amount of data being handled is too large. To avoid this, aggregators make use of keyword filters that include or exclude content based on user-defined keywords.

Clouds
Clouds act as update notification service for aggregators. This helps to prevent the website providing the feed from getting overloaded and also makes for more efficient use of Internet bandwidth. While the concept is good there are only a few websites that are currently making use of Clouds.

Online aggregators
There are many portals and ISPs that are providing online aggregation services. Online aggregators (like KickRSS) have certain advantages in that the user does not have to waste any bandwidth or check for updates, the software does it for them. Since there is nothing to install, anyone can use these aggregators through a regular web browser. These services are rapidly being merged with email, document handling, and desktop integration. News sites especially benefit from online aggregators as it allows them to deliver more user-specific content based on demographics and preferences. The same applies to advertising that is now more targeted and hence yields a higher conversion.

Desktop aggregators
These are regular software applications like a web browser or an email reader. The interface depends on the design where some go for a web browser like look and others prefer a conventional email client like look based on folder, trees, header, and content panels.

RSS feeds are published through web servers because they are most accessed servers of all and require no configuration on part of the user. This is all a plug and play concept where the user simply subscribes to an RSS feed and then the aggregator fetches all updates at predefined periods. Some aggregators are also including newer features like multimedia upgrades for audio and video, Internet browsing, email clients, and blog editors.

Meta feeds
End users rarely use these feeds. They are meant for the search engines and huge web portals that need aggregated content.