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Alerts are notifications, through email or a variety of other delivery systems, when materials of interest to you have been published or added to a database, websites, new publications within parameters of previous successful searches, etc.
According to Wikipedia, a blog is "a contraction of the term 'web log' and is a type of website, usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in reverse-chronological order."
There are many different types of blogs, including: personal blogs, corporate/organization blogs, or subject blogs.
Blogs can be monitored individually, using web browser bookmarks, or aggregated via an RSS newsreader service.
You can search for interesting blogs to add to your RSS feed reader by visiting Technorati, Google Blog Search, or Search 4 RSS.
But in all likelihood, the best method to discover RSS feeds is to visit the web sites you routinely visit and look for the RSS icon or some text indicating RSS availability (such as ).