Titles are a way to display some distinguished achievement a player has. Titles are usually obtained from beating the most difficult Challenges, but there are other methods for obtaining some titles.
Titles are separated by how common the title is among users. Titles are separated into five rarities/tiers, and can fluctuate over time. The fifth tier is the highest. Titles display above the player's head when enabled.
The Hero Title
The Hero Title is by far the most common title, since it's method of obtainment isn't insane to accomplish and infinitely available to obtain. In order to receive this title, you must firstly be the fastest player in the Weekly Challenge, then complete The Path of Heroes Challenge. It is a 3rd tier title.
The Hexagonal Title
This title is by far the most ridiculous one to accomplish currently, requiring players to beat the Hexa Challenge. Nobody currently owns this title. This is a fifth tier title.
The Mazecomp 2018 Title
All commands related to titles stem from the /titles command (not to be confused with the vanilla Minecraft /title command).
Setting a Title
/titles set <title>
Allows you to set your 'title display' to the title specified, if unlocked to the player.
Clearing a Title
Clears the title (if any) displayed above the player's head.
Listing Available Titles
Shows all of the unlocked titles you currently have (if any).
Seeing Your Current Title
Tells the player what title they currently are displaying (if any).