As an agent when you are working on tickets or accessing articles, characterizing them by adding a tag would help to track and segregate them with respect to issues or requests. 

Go to Admin > Agent Productivity > Tags > Add tag and add the required tags for the helpdesk. Each tag has a character limit of 32

Once a tag is created, you can associate it with Tickets, Contact, and Articles. You can merge two tags by editing one of the tags and giving it the same name as the other.

Upon adding a tag: