Skills

Skills are the trainable abilities that the player can level up during his adventure. Any skill can be trainable by performing actions relatable to that skill. Cutting down trees to get experience in Woodcutting is a great example. Many of the skills make up for each other, so that the player can cut a tree to train Woodcutting, use the logs he got from Woodcutting to train Firemaking. Then he can cook food on the fire he created to train Cooking, and catch more fish by training Fishing. All the fish can be used afterwards to train Combat and Slayer which will grant you several items that'll allow you to train other skills, eg; Herblore, Construction, Summoning, etc. You can also use lamps to get experience in skills, but the experience you get is based on your level. The higher levle, the more experience you'll get. The higher level you have in a skill, the rarer resources you'll be able to get. Training certain skills will result in a profit, will training others will result in a loss. Many players tend to use lower tier resources to get the highest experience in a skill that gives a loss. Another method is to gather the resources yourself, instead of actually buying expensive skilling material. To gain profit from some skills, players sell the resources that they manage to aquire to other players. Please see the money making guide for more information.

The only exception is hitpoints, which starts at skills start out as level 1, where you have 0 experience at first. The on level 10 where you'll have 1,154 experience to start out with. All the skills have a maximum level of 99 and maximum experience is reached at 200,000,000. Dungeoneering can get up to 120 though because it is one of the fairly newer quests added to this revision. It is still debatable if all the other skills should have their max level raised to 120[1].

- More To Come -
 * 1) ^ Confirmed by Mark that the max level of all stats in Fortis; Survival would be increased to 120, with a potential introduction of master capes, new methods to get armor and resources and access other content. (http://prntscr.com/8w3s0v)