"what is a backbencher?"

In the Australian Parliament there are both frontbenchers and backbenchers. Frontbenchers sit in the front row of seats in either the Senate or House of Representatives. Frontbenchers are either ministers or shadow ministers. Backbenchers are members of parliament who sit behind the frontbenchers on the back benches.

Backbenchers have an important role in the Parliament. They debate and vote on bills (proposed laws), raise issues of concern to their electorate or state/territory and participate in parliamentary committees. Backbenchers are also members of their team and help to make decisions with their team, such as who will be the leader of the team and how to vote on bills. 

More information on backbenchers can be found here.

diagram to help explain what is a backbencher?