Skills are a player's attributes that can be advanced throughout the game. Skills are trained by repeating actions that give a chance to increase in skill level. Skills range from cooking food, to chopping trees and to casting magic. Some skills are "interlaced", meaning that they can be used together. For example, logs obtained from Woodcutting can be lit for Firemaking, which can then be used to cook food for Cooking.
There are 51 different skills in Outlands.
All skills start out at level 1 except for Hitpoints, which starts with level 10. Players can advance a skill to level 99. After that, they can increase their experience up to 200,000,000 but get no more levels for doing so. See Hiscores for the relative rankings of the different skills.
Skills can be temporarily boosted through special equipment, items, Prayer, or potions.