There are a number of different types of people that you come across in the workplace. Some are more than happy to sit back and let others lead, whilst some are more comfortable with taking the reigns and acting as the leader.
Although you can switch between these roles, and a lot of people do, it's likely that you fit into one description more than the other.
Not only does this help you to become more efficient at work, but it also lets other people know of your skills and allows you to work better in a team.