Impression share tells you what percentage of the time your ad was shown compared to how many times it could have been shown. For example, if your impression share is 40 percent, it means your ad only appeared in 40 out of every 100 possible searches. A low score usually means your budget is too small or your bids are not competitive enough. Beginners should pay attention to this number because it helps you understand if you are missing out on potential customers. It is a simple way to see how visible your campaign really is. What impression share are you currently getting on your active campaigns?