The Achievement Diary (also known as Diaries or Tasks) is a set of small challenges that players may complete in order to earn rewards. The achievement diary consists of tasks that are usually tied to a specific area and are meant to test the player's knowledge about that area. There are currently eleven areas that have tasks to complete.
The tasks of each area are split into four categories based on their difficulty: Easy, Medium, Hard, and Elite. The easiest tasks usually do not require any significant skill levels to complete, but most higher level tasks require the player to have high skill levels and difficult quests completed, as well as in-depth knowledge of a particular area within RuneScape, such as the TzHaar Fight Cave. The Achievement Diary is currently exclusive to members only.
Diary difficulty is sorted by levels needed to complete: Easy require skills up to level 40, Medium up to level 65, Hard up to level 75, and Elite can require skills in the 90s. For this reason, if you are pursuing to complete all of a specific difficulty of diary, it is recommended that you have all your skills at the diary difficulty level.
Should you complete all tasks of one difficulty without having completed the tasks for the previous difficulty for one area, the taskmaster will tell you to complete all of the tasks of the previous difficulty before claiming your reward.