For Paladins, each talent tree allows the paladin to assume different roles in a party or raid.

The 3 talent trees are as follow:

Holy
This talent tree transforms the paladin into a powerful healer known for its low aggro generation and mana efficiency in PvE. In PvP the paladin healer (or Healadin) has high survivability due to his plate armor proficiency and protective spells such as Divine Shield. Also if the right gear are collected, paladins specced in this tree can be a powerful spell-damaging class known as the Shockadin.

Protection
Paladins in this talent tree play the role of a Tank in a party/raid. The Protection paladin (Tankadin) is efficient in tanking multiple mob and is another substitute to the tanking warrior other than the feral druid. Unfortunately the Tankadin is widely not regarded as a end-game raid tank as he lacks the damage mitigation and high HP requirements compared to a Protection-specced warrior.

Retribution
This tree sacrifices the tanking and healing ability of the class and focuses solely on dealing damage. In this tree paladin focus on warrior stats such as Strength, Agility, Stamina and Critical strike rating to achieve high damage potential with Seal of Command. Carrying a heavy two-hand weapon he can be a powerful opponent. However in PvE, Retribution paladins (Retadin) bring little utility to the raid unlike shadowpriests, and lacks aggro control. In PvP the emergence of Resilience, which reduces critical chance and damage has weakened the Retadin due to his reliance on high critical damage.