Experience is a level of your character that increases by killing your enemies.. Max level for your experience is 70 as now, and after reaching this level, you can start looting Champion levels that will start from a zero.
This experience is obtainable from normal monsters or Daily quests, that each quest gives you same amount of experience and same amount of Gems. Take a note of the fact that summoned enemies, such as skeletons, merlok toads and many others are only killing packs that can drop only Gold.As your advance further, the time to level up also increases as long also the experience needed for you to reach next level.
By gaining next hero levels,, you can unlock Abilities for your character and grow stronger.
Monsters has also their level.. They do obtain certain buffs as they level up, but the same fact is about your hero.