How election results are calculated and reported?
How do you win an election in Scotland, and how will the BBC report the results? Key questions are answered below.
How is the Scottish Parliament elected?
There are 129 seats in the Scottish Parliament.
Elected members, known as Members of the Scottish Parliament or MSPs, are chosen using the Additional Vote System.
Voters have two votes each.
The first is used to select a constituency member to represent their local area. There are 73 constituency members in total, representing the 73 constituencies.
The second vote is used to elect seven regional members, who represent the wider region in which the constituency lies.
There are 56 regional members for the eight Scottish Regions.
Constituency members are elected using the "first past the post" system, where whoever achieves the most votes is declared winner.
Regional members are elected using a form of proportional representation, in which seats are allocated based on parties' share of the vote.
Major parties submit a list of candidates for each region, who are elected in order based on the number of votes the party receives.
The eventual number of seats awarded is adjusted to take into account the number of constituency seats that party has won in that specific region.
How do you win?
A party wins the election - and can form government - if it wins more seats at Holyrood than all the other parties put together.
There are 129 seats, so 65 seats are needed for an overall majority.
What is a constituency?
Also called a seat, constituencies are the election's political battlegrounds.
Although they vary in size geographically, they are all intended to contain roughly equal numbers of voters.
What is meant when a party wins, holds or gains a seat?
What matters most is how many "seats" each party wins, and for things to change political parties need to win seats from each other.
Because winning seats from each other is so important, a special language is used to show this. Seats that are won can mainly fall into two categories: "hold" or "gain".
Hold: If a party wins a seat that it won in 2011, this is described as a "hold".
Gain: If a party wins a seat that it did not win at the last general election, this is called a "gain".
Win: Where there has been a by-election since the last election and that by-election resulted in a different party gaining the seat compared to the general election result.
For an opposition party to form a new government, they need to win seats from the existing government and other parties to make "gains", while they retain or "hold" all the seats they had last time.
Equally, incumbent governments will seek to defend or even extend their mandate by holding all their current seats, and gaining new ones from other parties.
What is a by-election?
By-elections are one-off elections in seats where, for example, the sitting MP has stood down or died.
There have been three by-elections in Scotland since the 2011 election - in Cowdenbeath, Dunfermline & Aberdeen Donside.
However, when reporting the results of the 2016 election, the BBC will ignore the results of these to allow for a straightforward comparison with 2011's seats.
Some of the terminology used to describe results in by-election seats is different.
For example: In 2011 Bill Walker won Dunfermline for the SNP, but resigned after being convicted of assault. Labour's Cara Hilton won the subsequent by election.
If the SNP regains the seat in 2016, the BBC will describe this as an "SNP WIN", not a hold or gain. It will not appear as a net gain in the overall SNP seat tally.
However, if Cara Hilton retains the seat, the result will be described as "LAB WIN", and will appear as a net gain in the Labour seat tally.
The BBC does this in recognition of the very particular circumstances which often surround and shape the outcome of by-elections.
Comparing seat change with the previous Holyrood election represents a fairer way of representing how the political expression of voters has changed.
What is a majority?
To achieve a majority a party must win one more seat than all the other parties added together.
Having a majority means a government can enact its policies more easily and without the need to forge alliances or rely on support from other parties.
The mixed member proportional representation system at Holyrood means a majority is harder to achieve in the Scottish Parliament than Westminster.
In the four elections since the parliament was formed in 1999 only one - 2011 - has resulted in a party winning a majority.
Which parties appear in the summary results graphic at the top of the BBC News website?
The results graphic always displays the top five or six parties in terms of seats won.
If more than six parties win seats, the parties with fewest seats are amalgamated into a grouping called Others.
In the event of a tie - eg two parties have two seats - the party with the most constituency votes nationwide will be named.
After the first batch of results, BBC analysts will be able to forecast how many seats the parties are likely to achieve overall.
This will be shown as grey shadow bars, marked as "Prediction", and may change as results unfold on election night.
Which parties are listed in the overall results tables?
To appear as a named party in the constituency seats scoreboard a party must
- Be fielding 10 or more constituency candidates across the country
- Have achieved greater than 1% of the constituency vote at the last Scottish Parliament election
- Had a sitting constituency MSP in the last parliament
Any parties which do not meet these criteria are amalgamated into a group called Others.
To appear as a named party in the regions scoreboard, a party or independent candidate must
- Be fielding 10 or more candidates
- Achieved greater than 1% of the vote in the last election in overall regional voting
- Had a sitting regional member in the last assembly
Each individual constituency or region page will always name every party and candidate standing in that constituency or region.
Each constituency or region page will always name every party and candidate standing in that constituency.
What are the abbreviations used for parties?
On smaller mobile screens, parties are sometimes abbreviated to 3 or 4 letter codes. Codes used in Scotland are:
AWP: Animal Welfare Party
CON: Scottish Conservative Party
CPB: Communist Party of Britain
CSSI: Clydesdale and South Scotland Independents
GRN: Scottish Green Party
LAB: Scottish Labour
LD: Scottish Liberal Democrats
NF: National Front
RISE: Respect, Independence, Socialism, Environmentalism
SCP: Stronger Community Party
SLBP: Scottish Libertarian Party
SNP: Scottish National Party
TUSC: Trade Unionist and Socialist Coalition
UKIP: United Kingdom Independence Party
UP: Unionist Party
WEP: Women's Equality Party
Why does the postcode search not give the result I expect?
The postcode search box uses the latest available data supplied by Ordnance Survey.
Discrepancies can occasionally occur when a postcode search returns a different constituency to the one given on polling cards sent to an address at the same postcode.
Normally the constituencies concerned are next to each other, and it appears these discrepancies occur when postcodes are on the border between the two constituencies.
We would advise people affected to follow the information on their polling card in terms of the constituency they are in and the polling place to be used on 7 May.