Slayer skill has been part of the game for a good long while now. So lets talk about it :
Slayer is one of the essential skills in runescape. It lets you undertake special slayer tasks and kill monsters which you otherwise cant find. Tasks are composed of getting a number of points by killing certain enemies.
When you finish a slayer task you get a certain number of slayer points which are limited to 64 000 at a single time, however its not a strict limit. The best way besides completing tasks to get slayer points is to trade in the Tuska masks which grant you 20 slayer points each.
Masks and helmets
You can buy slayer masks at Vic, the Trader in Shattered Worlds. Each slayer monster has its own slayer mask and gives you various bonuses as well as it was used to get the corresponding slayer task. After you get enough mask points, by killing the requisite slayer monster your mask will upgrade to a slayer helmet, which is the pride and joy of every skilled slayer.