One of my friends once asked what you do on a server, so now im going to say the diffrent types and what you do on them:

Normal Vanilla survival
You just do what you do in single player, just make sure you get away from other players and there you can pvp
Faction
here you basicly make or join a "clan or club" and you work with other members and defeat all others. Your faction will build a base and claim it. You have "power" which is something you use to claim. when you die you lose power and when you get more members your factions gains power. If your power is more then another factions you can claim their land. You can ally another faction so they cant attack you and vice versa. You can enemy and attack them in their land and vice versa. YOu can have spys to go into othher factions and raid them.
Jail Server
Everyone is basiclly in a giant jail, where you can pay your way out. Theres pvp in all the halls, a mine, a shop, and a tree farm. You can sell things to get money and get out. There are gaurds who join the fight when there is pvp.
Zombie survival
In this server your in a massive town. There is no pvp (but sometimes there is) and the only mobs the spawn are zombies. You must survive.
Creative
People make creative servers where you are in creative mode. most of the time it only lasts a week due to greifers.
Red Vs Blue
There are two factions that Vs eachother
Roleplay
Everyone has a role to play in this server, if you dont know what roleplay is, your stupid

Please comment on ones i miss