Subscriptions, or feeds as they are commonly called, are simple ways for web publishers (bloggers, podcasters, news sites, etc.) to notify interested individuals when the publisher's online content changes. Subscriptions or feeds save you time by not having to continually check a Web site to see if there is anything new. Instead, an short message, headline, summary, or alert is sent to every subscriber indicating there is something new to view on each selected site.
Interested individuals subscribe to feeds, through a feed aggregators, which give them access to all desired subscriptions in one location. Many feed aggregators are available. Some are standalome applications, others are add-in utilities to Outlook or your Web browser. Some feed aggregators are free while others require payment.