What is rss.how to use it in my blog.?

What is rss and rss feed.how to utilize it with my web log.is the following legal usually are illegal.

Some REALLY SIMPLY SYNDICATION feeds are free and some you need to pay pertaining to.All the methods listed at
http://www.feedzilla.com/rss.asp are generally free to apply (as a long way as MY SPOUSE AND I know).

It is advisable to have the parser on the site that could read your XML REALLY SIMPLY SYNDICATION output, that is then formatted for you to HTML using CSS hence your visitors could see it.I try a customized variation of RSS2HTML :
http://www.rss2html.com/ — which needs a PHP server to jog.