The 25 skills in RuneScape enable players to perform various activities within the game, allowing for interaction with NPCs, the environment and other players. Players gain experience points in a skill when they utilise it. For example, mining an ore trains the mining skill, and when the player accumulates enough experience points in the skill, their character will "level up". As the skill level rises, the ability to retrieve better raw materials and produce better products increases, as does the experience awarded if the player utilises new abilities. The total skill level of a player partly symbolises the player's status in the game and the official RuneScape high score tables can be viewed by subscribers. Upon reaching the highest available level in a skill, members may buy a special cape known as a "Cape of Accomplishment" or a "Skill Cape", to symbolise their achievement. A "Max Cape" can be purchased if a member reaches level 99 in every skill.

Some skills, such as woodcutting and fishing, enable the player to collect raw materials that can be processed into usable items for other skills, such as fletching and cooking respectively. The items created can be used by the player or sold to shops and other players. Other skills allow players to kill certain NPCs, build their own houses, move around the map with greater ease, steal from various NPCs, market stalls and chests located in-game, light fires, cook their own food, create their own potions, craft runestones and weapons, plant their own plants, hunt NPC animals, raid dungeons, and summon familiars to assist in combat and training skills.