Agility Is A Skill That Improves Your Movement
Agility is a skill that improves your movement. The advantages of a high Agility level are many: you will be able to access new locations, take quicker routes from place to place, improve your abilities in other skills, run further and recharge your run energy quicker. As well as allowing you to get through various obstacles, Agility is also used to recover energy spent on running.
The higher your Agility level, the faster your energy will recover, letting you effectively run for longer. Players with very high levels of Agility will find that they can move quickly around Gielinor. The more weight you carry, the faster you will lose energy while running.
You can check your run energy by clicking on the 'spanner' icon at the bottom of your player interface or looking at the run energy status globe to the right of your minimap.
By raising your Agility, you can also receive greater rewards from your Fishing, Thieving and Hunter skills. There is a chance of receiving bonus tuna, swordfish and shark when you have a high enough Agility and Fishing level; you'll get double, triple or quadruple loot when Thieving; and the you'll gain the ability to catch butterflies barehanded with Hunter.
Agility is mostly trained through the use of training courses. Throughout the land of Gielinor there are a wide variety of training courses which range from easy 'no-risk' courses for beginners, up to challenging high-level courses deep in the Wilderness. To proceed through each course you will simply need to left-click on the obstacle you wish to pass and, if you have the appropriate Agility level, you will attempt to do so, though you may not always succeed. Some obstacles are hazardous and if you fail them it can cause a loss of life points and prevent you from gaining experience for that attempt. Due to this, it is advised for most courses that you bring some food with you - it is down to you to discover which obstacles are safe or not. If you choose to follow the course properly, you will gain experience for each obstacle you successfully complete, as well as a bonus upon completion of the lap.
Those more advanced in the Agility skill will find that the gnomes and barbarians have an extra challenge available in the form of advanced courses. These start part-way through the courses, providing an optional challenge for improved experience, as well as the lure of new clothes to help out with your Agility training.