Online advertising continues to grow revenue while traditional means are flat to declining (newspapers for example); although it still is a small component of
overall advertising spend, online advertising is proving a most effective means for reaching your audience. An online advertising firm can help you maximize your benefits
Online advertising takes several forms. One is pay per click (PPC) advertising where you are only charged if your ad is clicked on and they visit your website. This form is used very successfully. One of the key strengths is that it is easy to understand the value.
Pay per impression (CPM) advertising is based on how many times the page that the ad was on was viewed (or potentially viewed). Something like a billboard in that the ad was there and available. These are typically charged at a rate per thousand views. These are especially useful for branding activities where your goal is to enforce the brand identity as much as get a sale
Pay per action (CPA) advertising charges when an actual closure is achieved. This would be a sale or a lead form filled out or whatever activity it is you are trying to accomplish.
It is difficult to determine which is the most cost effective for your situation. It depends so much on the details of the campaign. For example, a well positioned CPM ad can be extremely cost efficient wheras an ad placed in a low performing position on the page (such as the lower right) could yield very poor results.
The role of your vendor is to help determine which ads are most appropriate for your needs, how they should be structured and where they should run.