AdMob is one of the largest mobile advertising networks. It is one of the most popular ways to monetize mobile apps. It serves ads from over a million Google advertisers worldwide. As a publisher you get access to mediation tools to maximize revenues effortlessly while advertisers can take advantage of promoting apps to millions of smartphone and tablet app users across the AdMob network. You can also cross-promote within your own apps for free with house ads.
You can also use Google Analytics, which is available through the AdMob interface, to analyze you apps for better insights on promoting it.
With its ad filters, you have control on which ads you want to appear in your apps, maximize your earnings by showing ads from multiple ad networks with AdMob Mediation and use its optimizer tools for better conversions. You also get paid in your local currency.