Torrentz will always love you. Ability scores dungeons and dragons 4th edition dungeon master’s guide pdf give small bonuses to your dice rolls. Universal d20-based system of roll-over target numbers.
EXP’s to advance to the next level. Classes get features as they reach new class levels. Hit points, class-based hit dice. If a character has an ‘advantage’ for a skill roll or combat roll, the player rolls two d20 and takes the better one. If a character has a ‘disadvantage’, roll two d20 and take the worse one.
Attributes are the same ol’ six, but more important than before. They’re used for skills checks and saving throws. Ability score increases are now class features, meaning that you have the potential to lose them if you multiclass. Most classes get 5 ASIs, at levels 4, 8, 12, 16, and 19. Rogues get a couple extra, and Fighters get a couple more than Rogues. Feats are now fewer in number and more potent. If a character wants to obtain a Feat, they have to give up one of their Ability Score Increases to gain access to it.
There is a hard cap of 30, which cannot be exceeded by any means. DC 80 skill rolls, no more AC 120 monsters. Seems small, but see above about skill checks and ACs not getting stupid large even at high levels. Saving throws are like skills checks.