Each time an ad is displayed on the internet, it is called an “impression”. You may see this metric on your pay per click reports, and you might wonder what the relevance of this metric is. Well, for advertisers the number of impressions does not mean much unless it is put into context.

A poorly targeted campaign will have a higher than necessary number of impressions – this may be a problem because your ads are displayed when people are not particularly interested in seeing your ads. This may turn into wasted clicks and wasted marketing dollars because of poor targeting. In other words, if your PPC manager tries to impress you with impression stats, do not assume that a high impression count is, if you will excuse the pun, impressive!

However, the number of impressions is useful in quantifying relative traffic strength for a given period, and that is generally why campaign managers will include this metric in reports. For example, impression counts will vary with seasonal products & services, public holidays, weather, the economy – impression counts are the equivalent of shopping mall foot traffic: the less people that visit malls, the less business retailers will do. And the same rule applies to impression counts related to online shopping.

A sudden change in impression count could also be an indicator of some other problem with the PPC campaign, sometimes related to changes in the PPC system itself, or changes in campaign settings.

Campaign managers also use impression counts to measure the effectiveness of the campaign as it is the basis of the click-through-rate (CTR).

CTR = # of clicks / # of impressions.

For example, if an ad was displayed 300 times and was clicked on 14 times, the CTR would be 14 / 300 = 4.67%. In other words, on average the ad was clicked 4.67 times for every 100 impressions.

Lowering the number of invalid impressions by improving ads and improving keyword selection will result in a higher CTR and a better quality score for the campaign. This in turn may help lower the cost of the campaign because the top tier pay per click companies reward advertisers for delivering quality campaigns.

So, if your PPC manager highlights the impression count and touts it as a significant metric without putting into context, have a good chuckle! In short, impressions ought not impress advertisers, but this number is very important in understanding campaign effectiveness.