The role of the Scottish Parliament's presiding officer is central to Holyrood as an institution.

It is a job that comes with great responsibility through organising how the Scottish Parliament functions.

The presiding officer deals with issues such as what food and drink services are on offer to what questions the government must answer - it is a role with a wide remit.

On Thursday, members of the Scottish Parliament will elect the fifth presiding officer since legislative devolution in 1999.

The new officer will join David Steel, George Reid, Alex Fergusson and the outgoing Tricia Marwick as those who have held the title.

Holyrood's presiding officer has four main roles:

1. Chairing business in the debating chamber and selecting questions to the First Minister plus supplementary questions and amendments.

2. Overseeing the parliamentary bureau which crafts Holyrood's parliamentary business agenda, including placing deadlines on the passing of legislation.

3. Holyrood's corporate body is chaired by the presiding officer. It deals with the parliament's own spending over staff, accommodation and services.

4. To represent the Scottish Parliament domestically and across the world.

By convention, all presiding officers are invited to join the privy council which advises and informs the Queen on political matters. This forms part of the office's domestic diplomatic function.

The new presiding officer will be paid £45,605 on top of their annual salary as an MSP. This means the office holder will earn a total salary of £106,290.

When an MSP is elected to the office they must renounce their party membership and any other political affiliation.

The presiding officer must be strictly non-partisan in both his or her work and in activities outside Holyrood.

The most public role of the presiding officer is bringing debates in Holyrood to order and maintaining that order to allow MSPs to make their points and ask questions.

To do this he or she will call for order and strike her gavel to bring the chamber to silence.

As a last resort, the presiding officer will stand to bring the chamber to order if the members who are being disruptive have refused to do so.

In the last parliament the closest that the presiding officer came to standing is when James Kelly MSP refused to sit down after the presiding officer began to speak:

The current declared candidates for the selection: