Skill Checks and class exploration skills
Each class has a specific skill that allows you to interact with various objects in the game, some of which are containers of various items, some may temporarily enhance the character or discover the secret passage. Containers with different items are called Skill Checks.
Those Class Skills are: Dungeoneering, Thievery, Religion, Acana. Although each class has only one type of skill, you can buy a kit replacing other skills. Kits do not have a 100% chance of success, so try to always carry a spare.
Using those class skills or kits during the exploration you can collect some valuable materials for crafting and some bonus enchantments or runes.
Each class has it's now progress path called Paragon Path. On level 30 you will have to choose what path suits you best, this will determinate how your hero will progress, what abilities he will have, etc.
Future Daily, Encounter, class features and At-will skills will differ depending on Paragon Path you will choose.