Ad campaigns consist of ad groups. In Adwords, campaigns allow you to choose the campaign types such as showing your ads on search and/or display networks. It also allows you to set the geo-targeting, whether you want to target people in Australia or United States. Maybe your website is only in one language. You can set which languages you want to target such as people who speak English or French. You can also set your bid for mobile devices. For example, if your website is not mobile friendly, you may put a -100% for mobile so your ads won’t show up for users who are on their mobile device.