Pay-per-impression ads refer to banner ads that generate revenue when visitors come to a site.  A website owner is compensated for the simple fact that the ad is displayed on his/ her site when a visitor comes.  As this method of advertisement is based on the number of views, website owners can rely on it as a steady source of income, although compensation per view is relatively low.  Also, it is important to mention that a website owner is only compensated when there is a "paid view," meaning that there is actually an ad displayed.  When there are no ads displayed, those views are commonly referred to as "default views" and generate no revenue.

The main pay-per-impression programs are:

• Tribal Fusion
• ValueClick Media
• Burst Media
• Casale Media

There are other pay-per-impression programs, but they tend to have a very exclusive membership based on very high traffic volume.

Intermediaries that offer pay-per-impression ads often offer a wide selection of them, meaning that you are bound to have junk ads appear on your site.  A good idea is to use the filter options that are made available to filter out the categories of ads that you don't want to show on your site.  If you are running a credible website, ads that you may want to filter out are typically:

• ads that have too much animation;
• ads that promote violence or sensitive subject matters;
• competitive ads; or
• ads that simply do not relate to the theme of your site.

* Some people views advertisements as adding to the content of a site.  That position is justifiable if the ad is theme-related and offers a useful product or service.

Pay-per-impression intermediaries also offer pop-up ads.  These ads are intrusive as they pop-up when people land on a site or leave a site.  If you run a credible website, it is not recommended that you display these ads, although it may be tempting.  Good Web development is about striking a balance between making money and providing a good user experience. 

Tribal Fusion

Tribal fusion offers a first-tier pay-per-impression program.  They restrict entry into their program to websites that have a minimum of 2,000 unique visitors per day, a credible layout and an active user base.

Burst Media

Burst Media is a second-tier pay-per-impression program.  It is on the high end of second-tier programs however as most of its advertisers are established businesses.  It offers advertisers the option of choosing to advertise on specific sites.  If an advertiser chooses that option, the rate will be much higher.  Hence, another reason to maintain a credible site so that big businesses will want to advertise on your site.

ValueClick Media and Casale Media

ValueClick Media and Casale Media are second-tier pay-per-impression programs.  They offer a good selection of ads and can be used to fill-up the gaps left by other programs.

Following are some basic tips to improve the performance of pay-per-impression programs:

• Increase your traffic... this is an obvious one.
• Increase your traffic from targeted geographical locations (such as the United States, the United Kingdom, Canada, Australia).  Advertisers target their audiences and will exclude audiences that are irrelevant to them or will pay more for a more relevant audience. 
• Choose your pay-per-impression program and give priority to the ones that pay more.  This may sound obvious, but many people only choose one program whereas they could have chosen many and ranked them in priority order to utilize all their impressions.
• Maintain a professional look and feel to your site.  Some advertisers choose to run their campaigns only on specific sites.  Those programs tend to have a higher CPM.  A professional look is also important to be accepted in the big league.  Unless your site is credible, you will not be accepted in those programs that pride themselves as having a good base of "leading-edge" or "professional" websites.
• Maximize the ad units on each page of your site.  Try to put 3 ad units per page.  That will roughly triple your earnings.  To be able to put 3 ad units without affecting the credibility of your site, however, you will need to rework the layout of each page to reach a good balance between content and advertising.
• Filter out the bad ads.  You will sometimes be asked to play gambling ads or violent ads.  You may choose to run those ads, but some other advertisers may not like that and may disregard your site on that basis.