Once you hit Level 10, your character immediately receives its first talent point. These are spent in talent trees, of which each class has three.
Each tree provides the character with unique abilities. Paladins, for example, can put their points into Holy, Protection, or Retribution. The Holy tree contains options that boost healing spells and provide greater flexibility for healers. Paladins that put their points into the Protection tree are rewarded with more health, and more abilities that allow them to serve as tanks, which will be explained when I get to the first dungeon rundown. The Retribution tree is for those who want to provide a massive output of damage. In the antiquated talent calculator shown above, each class would get a talent point at every level and get gradually stronger, getting some core spells around the Level 20, 30, 40 and 50 milestones. However, the game developers thought that it was silly for players to get their 'core' abilities at Level 50, so the system was redesigned.
Now at Level 10, players choose the tree that they wish to put points into, and are immediately given one of the core abilities of that tree. For example, a Protection paladin immediately receives an ability that allows it to throw the shield like Captain America, hitting up to three targets and causing a large amount of damage. Protection Paladins used to have to wait until Level 50 to get this, and now they get it much earlier so that they can get used to using it.
The talent tree provides a great deal of flexibility for a player, and for some classes like shaman, druids, and paladins, every tree can provide a unique experience.