The process for Labour's leadership elections varies according to whether or not a vacancy exists at the head of the party.
IF THERE IS NO VACANCY
Should anyone wish to challenge the leadership, they can seek nomination before the autumn gathering.
They may only proceed if they gain the support of 20% of Labour MPs - which currently means 71 people.
There can also only be a leadership election in these circumstances if the majority of Labour party members at the conference vote in favour of a challenge.
The candidate must then inform the party's general secretary and must win a further vote of party members allowing the challenge to go ahead.
IF A VACANCY EXISTS
Things change when there is a vacancy, if, for example, the leader resigns or becomes incapacitated.
When this happens, the Cabinet can liaise with Labour's administrative body, the National Executive Committee
(NEC), on whether to appoint an interim leader
until the next annual conference.
This person does not necessarily have to be the party's current deputy leader.
However, if the party is in opposition, the deputy leader will automatically "act up"
and the NEC will decide whether to hold an immediate ballot
or to wait until the next party conference to do so.
Any potential candidate needs to secure the backing of 12.5% of all Labour MPs before they can put themselves forward. Currently that means they need the backing of 44 Labour MPs, as well as themselves, to be able to stand.
THE VOTING PROCESS
The decision lies with an electoral college split equally three ways between the 354 Labour MPs and the Labour MEPs, all party members and members of affiliated trade unions who have not opted out of paying a political levy - about 700,000 people in the last Labour contest in 1994.
It is likely that up to a million people will have a say in the leadership race this time.
The ballot must take place at such a time which means the results can be declared at the annual party conference or at a special leadership election conference.
If any candidate receives a majority of votes, they are declared the leader. If not, the last place contender drops out and their second preferences reallocated - and so on until someone passes the 50% figure.