A view-through conversion refers to a special type of conversion that let’s you track the number of people who see your ad, do NOT click on it, but then ultimately find their way to your website and convert into a customer or lead. View-through conversions are only measured for ads that run on the Google Display Network. If you are really serious about understanding the ROI of your ad budget, view-through conversions should be a part of your plan.
Note: when view-through conversions were first available, you needed to take an extra step to “de-duplicate” them in your reports. In other words, if someone saw an ad, didn’t click, then later saw another ad and DID click, then your reports would show both a view through conversion for one ad, and a converted click for another ad. This is no longer the case, as Google automatically de-duplicates view-through conversions in AdWords.