Explorer Jack is the person who starts the Lumbridge and Draynor Tasks. The house is just west of the Lumbridge general store. He likes to help anybody that needs it, and is very useful. One of the rewards is an explorer ring, it regenerates 50% of running energy. Once one of the three tasks (Beginner, Easy, or Medium) is completed, players may start the next task, or talk to Explorer Jack to get the reward for the Beginner task. The rewards for Easy and Medium tasks are given by Bob in Lumbridge and Ned in Draynor Village, respectively.
He is also the starting point for the 2008 Christmas Quest, Myths of the White Lands, where he asks the player to collect "mysterious stones" from the Land of Snow, in which it is revealed that he is acquaintances with Sedridor's brother, Isidor. If the player logs out or talks to Explorer Jack fifteen minutes later, he will say he sold the stones and will give 5,000 coins as part of the profit. He will also give you rewards for any other tasks you complete throughout RuneScape.
Jack featured briefly in the old tutorial, Unstable Foundations, where the player reaches Lumbridge's surface through an arrow leading to his house. Roddeck knows of Jack, describing him as "an understanding chap; he won't mind us walking through his house," and the explorer expresses a lack of concern and even amusement at your discussion with him concerning the dragon. The 9 November2009 updates have caused Explorer Jack's chat to now have a chat option to end the conversation.
As of the new chat update, Explorer Jack's first line has been changed to "Click the green box below"