Pay-Per-Click (PPC) Advertising

Benefits:

drives targeted traffic to your web site very quickly
allows for testing of keyword phrases and offers
provides exposure on sites other than search engines

The two major vendors of pay-per-click advertising are Google Adwords and Yahoo Search Marketing. Each runs small text ads on the search results pages for your chosen keyword phrases. You also have the option to run those ads on their extended "content network" which includes other major sites and many smaller sites.

For most small businesses, search engine optimization is a more cost-effective long term strategy for achieving good visibility for targeted keyword phrases. But there are times when PPC is the best tool for achieving results:

your web site is not search engine friendly and cannot be made so quickly
your web site is new and may not achieve good Google rankings for several months
you are not ranking well in the "free" listings for particular keyword phrases
your business would benefit from increased exposure on the content sites used by Google and Yahoo