ShareSaveAdd as preferred on GoogleOn 7 May around 30 million people will be able to vote in elections across Great Britain.
There are votes for the Scottish and Welsh Parliaments and councils and mayors in some parts of England.
All 129 seats are up for election in the Scottish Parliament.
People in Scotland get two votes, one for their constituency and one for their region.
There are 73 constituencies in all and each elect one MSP. This is done by a first-past-the-post system of voting where the candidate with the most votes wins.
The other 56 MSPs are elected to represent one of eight regions. Each region elects seven members using a form of proportional representation.
There have been boundary changes for this election so some constituencies have changed name and shape.
The Welsh Parliament is expanding from 60 to 96 seats and a new electoral system is being introduced.
The boundaries are changing here too. The old constituencies and regions are being replaced with 16 new constituencies that will each elect six members using a system of proportional representation.
Voters get one vote for a party or an independent candidate.
There are more than 5,000 councillors up for election across 136 councils on 7 May.
They are standing for a mixture of district, metropolitan, unitary and county councils.
Elections are also taking place in all London boroughs.
Outside the capital there are elections in the West Midlands, the North West, as well as other areas scattered across England.
There are six county council elections, three in East Anglia and three in the South East.
There are also six council mayors up for election, five in London and one in Watford.
Produced by Wesley Stephenson, Jess Carr, Aidan McNamee, Allison Shultes, Steven Connor, Scott Jarvis and Chris Kay
