what is an impression 
an impression is a metric used to quantify the number of digital views or engagements of a piece of content usually an advertisement digital post or web page impressions are also referred to as an ad view they are used in online advertising which often pays on a per impression basis counting impressions is essential to how web advertising is accounted for and paid for in search engine marketing as well as measuring the performance of social media campaigns impressions are not a measure of whether an advertisement has been clicked on but how many times it was displayed or had potential eyeballs on it which leads to some debate as to how accurate the metric is 