Custom Tab is a plugin designed to display information to the player in the most convient ways. It does this by having custom tab columns that can be shown when the player meets certain requirements. It also takes advantage of the BossBar and ActionBar to display announcements or other info. It also makes use tags above the head to display a variety of information. It does this all completely asynchronous meaning it has little affect on server performance.
Take your time to read through this wiki to understand how the plugin works and solve any problems you may encounter
Take a deeper look at the plugins features here