Gaining experience and levels

For your character to grow, become stronger and fight more powerful opponents, you need to gain experience and earn levels. To advance to the next level you must accumulate a certain amount of experience points. That amount depends on your class and some other parameters. The human race needs 250 fewer points to gain a level than all other races.

HOW DO YOU GAIN EXPERIENCE?

Kill creatures, on your own or in a group with companions
Complete quests
Raise the percentage of a skill by using it in practice There is currently no option to turn off experience gain.

WHAT HAPPENS WHEN YOU GAIN A NEW LEVEL?

Your hit points, mana and movement increase
You can wear or use more powerful items and weapons
You gain access to new and interesting skills and spells, yay! Use the command skills all to see at which levels new skills and spells will become available.

WHAT AFFECTS THE AMOUNT OF EXPERIENCE?

The level difference between you and your opponent: kill enemies more experienced than you to get more experience. You can find out how much more experienced your opponent is with the chances command.
The difference in alignments between you and your opponent: for example, an evil character gets more experience for killing a good opponent than a neutral one.
The number of players in the group: if it exceeds 5, experience is slightly reduced. A group of up to 5 players does not affect experience.
The number of followers (charmed creatures, pets) in the group -- each such helper slightly reduces experience for the whole group
The leadership qualities of the group leader
Calendar bonuses and sacrifices

Spell and skill level can be raised above your "real" level through skills, artifact effects and other means.