Impressions in Google AdMob refer to the number of times an ad has been displayed to users of a mobile app. In other words, it is a measurement of the visibility of an ad. It is a vital metric in determining the success of an ad campaign. Impressions provide valuable information about ad performance, such as click-through rates (CTR), engagement, and conversion rates. To maximize the effectiveness of ads in AdMob, it is crucial to understand impression metrics and optimize your ad placements accordingly.

Making impressions in AdMob involves creating and publishing ads that are designed to be displayed within mobile applications. To do so, you will first need to create an AdMob account, which is free. Once you have an account, you can create ad campaigns and ad units. An ad unit is a container that holds the ads you have designed and allows you to place them in specific locations within your mobile application. 

To maximize your impressions, there are several strategies that you can employ. Here are some tips on how to make impressions in AdMob:

1. Choose the Right Ad Format
AdMob offers various ad formats, including banner ads, interstitial ads, native ads, and rewarded video ads. Choose an ad format that suits your app’s content and audience. For example, if your app has a lot of video content, you may want to focus on creating video ads. By using ad formats that resonate with your audience, you can increase the likelihood of them interacting with your ads, resulting in more impressions.

2. Optimize Ad Placement
Ad placement is an essential factor that can impact the success of your ad campaign. To maximize your impressions, you should place your ads in areas of your app where they are most visible and relevant to the user. For example, placing banner ads at the top or bottom of the screen can increase their visibility and the likelihood of users interacting with them.

3. Target Your Ads
Ad targeting is critical to maximize impressions. Targeting allows you to focus your ad campaign on specific groups of users who are more likely to engage with your ads. AdMob offers several targeting options, such as location, demographics, and interests. By targeting your ads correctly, you can increase their visibility and engagement, resulting in more impressions.

4. Optimize Ad Design
Ad design is an area that can significantly impact the success of your ad campaign. Your ad design should be visually appealing, relevant, and well-placed. Ensure that the design of your ads is tailored to the format you have chosen, and the content of your app. For example, using high-quality images and videos in your ad campaigns can increase their engagement and generate more impressions.

5. Test and Experiment
To maximize your impressions, it is essential to test and experiment with different ad formats, placements, targeting, and design. Testing enables you to evaluate the performance of your ads and identify areas for improvement. By experimenting with various ad strategies, you can optimize your campaigns over time and generate more impressions.

In conclusion, Impressions are crucial metrics in AdMob that determine the visibility and effectiveness of your ads. To make impressions, you need to create and publish ads within your mobile application, choose the right ad format, optimize ad placement, target your ads, optimize ad design, and test and experiment. By following these strategies, you can maximize your impressions and generate better engagement and higher conversion rates.