There are two types of Tags. All details can be found in our documentation TAGGING TRIPS
The API reference contains API methods for both types of TAGS:
Period TAG:
1.1. Activate Tag
1.2 Get list of all Tags
1.3. Deactivate a Tag
1.4. Deactivate all active Tags
Trip TAG:
2.1. Add a Tag to a Trip
2.2. Get a list of all Tags from a trip
2.3. Remove a tag from a Trip.