Variety is the spice of life and Guild Wars 2 completely understands the necessity of including a lot of variety in the game. Each profession in the game is given its own unique profession mechanic that helps separate the different playstyles. For the elementalist that mechanic is attunement. In short, each weapon contains four sets of skills, each set aligned to one of the four specific elements, and the elementalist can switch between the four depending on what role they need to fill.
Guild Wars 2