Routing is the process of forwarding packets from their source machine towards their destination.  Things that do this are called [Router Routers] and can be either dedicated hardware or a general purpose computer with two (or more) network interfaces.



[Router Routers]know where to forward packets because they share information on where machines are using a routing protocol.  There are many routing protocols, although only a few are widely used.



Routing protocols are often divided into two classes based on whether they are designed for use within a set of networks all run by the same owner (interior routing protocols), or are better for inter-domain routing (exterior routing protocols).



The other common classification is distance-vector protocols, which use a measure of how far it is to the destination to select the best route, or link-state protocols, which can use a more complex measure of the state of the connections.



[RIP] is a distance-vector protocol.  It was the first widely used routing protocol, designed at Xerox PARC, and was first used for the XNS protocol suite.  It was ported to IP, and has undergone several revisions.  It is now seldom used because it has quite poor performance in larger networks (and most networks now are large.) {/regexpicons/emoticons/emoticon-face3.png ;)}



[OSPF] (Open Shortest Path First) is the major non-proprietary interior routing  protocol in use for IP networks today. OSPF is a link-state protocol.



(http://rspf.sourceforge.net/ RSPF) (Radio Shortest Path First)



[IS-IS] is an interior routing protocol developed by the ISO as part of the OSI networking suite.  It supports multi-protocol routing and is also used for IP networks.



[BGP] is the major exterior routing protocol of the [Internet].



There are also some proprietary protocols in wide use: (http://www.cisco.com/ Cisco)'s [EIGRP] is perhaps the most common.



There are several developing protocols intended for use in wireless and mobile wireless networks.



Finally, a note on pronounciation:

* the English tend to say 'root' and 'rooter',

* Australian's tend to go for 'root' and 'rowter', although 'rowt' is also pretty common, and,

* in the US, 'rowt' and 'rowter' seem to be dominant.