From b2evolution manual
b2evolution has built-in support for RSS 0.92, RSS 1.0, RSS 2.0, and Atom feeds for both posts and comments. Anyone reading your site will automatically be able to discover your RSS feeds and subscribe to your site. Separate feeds exist for each individual blog on your site, or you could get a feed containing all the blogs on your site by subscribing to the Blog All RSS feed.
As well as providing a feed for users to read, RSS can be used to provide content from your blog for other websites, or other parts of your own website.
The history of RSS
You can read what François Planque (the creator of b2evolution) said about the history of RSS in 2004 on his blog.
How to use RSS on your blog
You don't need to do anything to set up RSS - it is ready to use as soon as you post to your blog. However there are a number of ways you can optimize your RSS if you wish to do so.
Simplifying RSS feed choices
By default, b2evo has eight different RSS feeds on each page: RSS 0.92, RSS 1.0, RSS 2.0, and Atom feeds for both posts and comments. This is quite a lot! Few readers will want to subscribe to more than one of these, and so you may wish to simplify the choices for them. One very simple way to do this is by editing the _main.php for your blog, and removing the items for the feeds you don't want to show. You will find them near the end of the sidebar. However this can reduce compatibility for those with readers which cannot handle all feed formats. Another way is to subscribe to an external feed service such as Feedburner which allows a single feed URL to be compatible with multiple RSS formats. You can then remove all the feed addresses in your _main.php and replace them with one link to the external service. Be aware that if you do this you will still need to direct the external application to access the correct RSS feed from your blog so do not delete these from your template before you have set it up and verified that it works.
B2evo also by default has autodiscovery enabled on all blog pages. This means that compatible browsers and aggregators automatically detect the RSS feed, and make it easy for the user to subscribe to it. IE7, FireFox, and Safari 2.0 all support autodiscovery of RSS feeds out of the box. You can find these autodiscovery links within the <head> tag in your _main.php. They look a bit like this:
<link rel="alternate" type="text/xml" title="RDF" href="http://your.server.net/index.php?blog=2&tempskin=_rdf" />
If you have reduced the number of feeds you offer, or have subscribed to an external feed service you will probably want to remove some or all of these links; and in the case of an external service replace them with a single one pointing at the external service. Do this by editing _main.php. Just delete the entire <link> tag for those feeds you do not want, and keep at least one. When using an external feed service you will want to have only one link and change the URL in it to the URL of your external feed. You will probably want to change the title too, as this is the text the reader will see when they are subscribing. You can put whatever you want in there.
Public and private posts in RSS
Only posts marked as "Public" will go out in your feeds, unless you are logged into your site, then you (and you alone) will receive Protected/Private posts. "Protected" posts (members only) will only be received by members who are logged in.
You can display an rss feed for one category using the tempskin=_atom (or tempskin=_rss2) parameter. For example, if you want to display rss feed for the first category use the following syntax: