Someone gaining a new level.
Skills are a player's abilities that may be developed throughout the game. Skills are trained by various actions which use that skill, which give experience in the skill, until enough experience is earned for the next level. Some skills allow players to cook, chop down trees, make fires, use magic, make runes, and so on. Professional Java programmers have estimated that Jagex utilised nearly 250 pages of straight-up coding using loops to achieve a single skill. Some skills support each other. For example, logs obtained from Woodcutting can be used for Firemaking, and fires from Firemaking can be used for Cooking food, and food can be used to replenish life points to help in Combat. The higher your levels are the more of the skill you will have access to.