Trudeau is about to name some parliamentary secretaries. So what do they do, exactly?

It's a job that can be seen as both a promotion and consolation prize — a reward for loyal members of Parliament and rising stars on the government benches and a way to soothe the sting of being left out of cabinet.

To be a parliamentary secretary is to exist in a unique, little-understood niche in Parliament — the middle benches, where the occupants are neither ministers nor backbenchers.

With Parliament returning Nov. 22, Prime Minister Justin Trudeau will soon name a fresh crop of parliamentary secretaries to support 38 ministers. Each will earn $18,100 on top of the annual MP salary.

But the pay bump may not be the real incentive. Many see the job as an audition for a future cabinet spot.

Since 2015, Trudeau has appointed 17 ministers who served first as parliamentary secretaries — including five of the eight new ministers named last month.

So what does a parliamentary secretary do?

According to a government guide, parliamentary secretaries can speak on behalf of their ministers in question period and during debates on private member's business. They are not supposed to be absent from question period when their ministers aren't in attendance.

They're expected to help shepherd a minister's bill through Parliament by liaising with MPs, fielding questions and defending proposed changes.

Outside the chamber, parliamentary secretaries can stand in for a minister at public events.

They waive the right to bring in their own private member's bills or motions "as this could give the appearance of endorsement by the government or the minister," the guide states.

They are also not permitted to chair Commons committees or be a voting member of a committee on a topic that falls within their minister's sphere of responsibility.

Cristine de Clercy, a political science professor at Western University, said that parliamentary secretaries are "often overworked and under-recognized."

She said parliamentary secretaries are "quite valuable" to the political process because they help ministers manage their workloads and help bureaucrats who may have "trouble accessing the minister's attention."

The role is important to prime ministers as well, de Clercy said. It serves as a tool of party discipline — "the carrot part of the carrot and stick equation" — and allows a PM to build a talent pool for future cabinet appointments, she said.