Local elections decide who runs local councils, which are also sometimes referred to as local authorities.
Councils control things like council housing, rubbish collection, recycling, parking, transport, roads and footpaths, parks, leisure centres and libraries.
Each council area in Northern Ireland is split up into different sections, which are called wards. Wards are represented by councillors.
People who live in each ward vote for who they want their councillors to be.
Councillors are elected using a voting system called the Single Transferable Vote. This is where voters rank candidates in order of preference. So they put a 1 on the ballot paper next to their first choice candidate, a 2 next to their second choice candidate and so on.
They can rank as many candidates as they like. So if they only want to vote for one candidate, all they have to do is put a 1 next to their name.
In order to be elected a candidate must reach a set amount of votes known as a quota.
The votes are counted in stages. In the first stage only first preferences are counted. Anyone who reaches the quota is elected. Any votes received over the quota are not needed by the elected candidate and so are transferred to that voter’s second preference.
If not enough candidates have then reached the quota, the candidate with the lowest number of votes is eliminated and the second preference of everyone who voted for that candidate is then added to the tally.
This process is repeated until three or four candidates have been elected.
If a council ends up with a majority of councillors representing one political party, then that party runs that council. If there is no clear majority, the council is said to be under no overall control.