In our continued effort to shed some light on common AdWords misconceptions, let's take a look at another frequently misunderstood nuance, using this paraphrased advertiser email as a starting point:

We run an ad in the content network that normally gets a huge number of impressions daily. However we made a very minor change to the ad and now it is getting 0 impressions in the content network. Why did this happen? We really need this ad displayed in content, and not being there has reduced our sales dramatically! - Confused and curious.

So, why did this happen? Most advertisers are aware that while new ads may run on rather quickly, they must be reviewed and approved before they may be sent to our search and/or content networks. However, it's not so well understood that editing an existing ad, even if the change is very small, will also require review and approval before the ad may be once again sent to the networks.

Why is this so? Changing a single word (or sometimes even a single letter!) can give a line of text an entirely different meaning. With this in mind, and to ensure that we're delivering appropriate and high quality ads to our search and content networks, even these tiny changes need to be reviewed.

Here's a bonus tip to consider the next time you wish to edit an ad that is already appearing on the networks (it's used by many an expert advertiser):

Rather than editing an ad, consider leaving that ad as-is -- and then create a second ad (with your desired changes) in the same Ad Group as the original ad. Then, let both ads run until the new ad has been reviewed and approved. At this point, if it turns out that the new ad is performing better than the original, it may be time to delete the original.