Gary is thinking about rooting his old Android phone. Leo says that rooting means he can run his phone as an administrator, or "super user." Some companies, like Samsung, make it a bit harder to do, but it can be done.
Gary should check out XDA Developers.com. Two popular boot loaders include Clockwork Mod, and Twerk. But he'll have to use the exact rooting instructions for his specific model phone. And it varies from model to model.