Welcome to WebmasterWorld Guest from 188.8.131.52
Welcome to WW,
Depending on your requirements there's a bunch of scripts available that will do the job. Many are free, some have a small fee and others are full-priced application packages.
Do a search on Google for search engine script and you'll come up with a host of possibilities. Any of the questions you might have on installing or using any of them can be answered by many of the folks here on WW.
As a first port-of-call, take a look around hotsripts.com, and if you are on a unix platform, then Perl or PHP will be your best bet.
I have not used it myself, but ht//dig is supposedly very good aswell.
There have been multiple topics here about ht//dig before, so many of your questions will be answerable by reading these posts. if not, just ask ;)
On-site search consists of the scripts that you host on your web site. WebmasterWorld's site search usesa mod of FDSE [xav.com].
You can find a list of hosted search [directory.google.com] services here. The service has limits on the number of pages or the serving of ads in exchange for site search.
The advantage of on-site search is that you can customize the layout to your liking. Remote search is easy to setup and does not utilize your server space.