Google Adwords can be a great marketing tool and although it is often not cheap it can obtain you some fantastic results very quickly. It is the most popular choice for Pay per Click advertising and once set up is easy to manage.
The idea of pay per click ads is that you pay to have your advert shown on the google listings pages or on the ad network. When your ad is clicked they visitor will be taken through to a page on your site and you will usually be charged for that click (depending on how you have the ad campaign set up). The beauty of AdWords is that you do not have to wait for the search engines to index your site, instead you can get to a number one spot on Google almost instantly. This can be vital if you have a product launch or have a limited time deal on that you want to promote as the indexing process can take weeks and there is no guarantee that you will get a top spot in the organic listings.
The way you set up Google Adwords is very important as if set up incorrectly you can end up wasting a lot of your budget for very little return.