In-market audience targeting consists of people:
- who are currently researching options and actively considering buying a product or service like yours
- who are in your overall target demographic group
- whom you’ve reached through remarketing
- who are interacting with contextually relevant content
Explanation: Select from these audiences to find customers who are in the market, which means that they are researching products and are actively considering buying a service or product like those you offer. In-market audiences are available to advertisers in all AdWords languages.
Read more here: https://support.google.com/adwords/answer/2497941?hl=en