Public bill committees, formerly known as standing committees, are given the task of applying detailed, clause-by-clause scrutiny to legislation at committee stage.
A minimum of 16 MPs are appointed, whose political affiliation reflects the relative strengths of the parties in the Commons - so a government majority is always guaranteed.
Traditionally, all bills were dealt with in a committee of the whole House.
But the innovation of standing committees brought with it certain advantages - membership could be granted to MPs with a degree of expertise in the policy area of the proposed legislation.
When standing committees were renamed public bill committees, they were also given the power to call witnesses to testify at evidence sessions on the proposed legislation.
Once each committee has collated its findings, it submits recommendations to the Commons which are debated at report stage.
The House of Lords does not appoint public bill committees - instead it usually debates proposed legislation in a committee of the whole House.