A more thorough explanation:

The Index of Trademarks is a yearly publication by the U.S. Patent and Trademark Office. It contains a list of all the trademarks that were registered in a particular year.

For example, the Index of Trademarks for 2020 would list all the trademarks that were registered with the U.S. Patent and Trademark Office in 2020. This could include trademarks for products like Nike shoes or Apple iPhones, as well as trademarks for services like Uber or Airbnb.

The Index of Trademarks is a useful resource for businesses and individuals who want to make sure that their proposed trademark is not already in use. By checking the Index, they can avoid infringing on someone else's trademark and potentially facing legal action.