Your client wants to show ads to people who’ve visited her website before. Which AdWords feature would you recommend she use?
Dynamic Search Ads
Remarketing lets you show ads to people who’ve visited your website or used your mobile app. When people leave your website without buying anything, for example, remarketing helps you reconnect with them by showing relevant ads across their different devices.
Remarketing helps you reach people who have visited your website or used your app. Previous visitors or users can see your ads as they browse websites that are part of the Google Display Network, or as they search for terms related to your products or services on Google.
Read more here: https://support.google.com/adwords/answer/2454000?hl=en