Often I get questions on SLP, what it exactly does and how to implement it.
To answer the first question. SLP stands for ' Service Location Protocol '.
What it does is already in it's name: It's a service running on one or more systems, that hands out a list of services to your clients specifying what services can be found on your network - instantly, without the need to have the clients ' go out and look '.
It can loosely be compared to DNS, which also helps to centrally resolve. With DNS you can resolve system names and certain services (the mail MX for example) to ip addresses and visa versa.
SLP on the other hand, is specific to making it easy for your networked clients to find out where a service is running they are looking for (e.g. location of printer services, timeserver, authentication sources like eDirectory, etc). The service list is built up dynamically and has more detail.