In football, a free agent is a player who is not under contract with a club.
That means they are free to agree a deal with any club that makes them an offer.
Players' contracts may expire because their club no longer wants them, because the player has chosen to move, or because a parting of ways suits both parties.
When a free agent signs for a new club, they are often paid a signing-on fee - the name given to the money a club pays a player when they first join. Allowing a contract to expire with one club, before signing a new contract with another, can prove very lucrative for a player.
The majority of major football leagues run from late summer to late spring, with pre-season in June and July. Therefore, contracts across most divisions typically expire at 23:59 on 30 June each year.
BBC Sport has taken a look at which players will be free agents on 1 July.
Those whose contracts are expiring but have already agreed transfers to new clubs are not included, as they will not become free agents.
Image source, Getty Images
Both Christian Eriksen and Victor Lindelof are leaving Manchester United
Which Premier League players will be free agents on 1 July?
Arsenal: Thomas Partey
Aston Villa: Kortney Hause
Brentford: Josh Dasilva, Ben Mee
Brighton: N/A
Bournemouth: N/A
Burnley: Ashley Barnes, Josh Brownhill, Michael Obafemi, Nathan Redmond, Jonjo Shelvey
Chelsea: Lucas Bergstrom
Crystal Palace: Joel Ward
Everton: Asmir Begovic, Dominic Calvert-Lewin, Abdoulaye Doucoure, Idrissa Gueye, Michael Keane, Joao Virginia, Ashley Young
Fulham: Tom Cairney, Kenny Tete, Carlos Vinicius
Leeds United: Sam Byram, Junior Firpo, Joshua Guilavogui
Liverpool: N/A
Manchester City: Scott Carson
Manchester United: Christian Eriksen, Victor Lindelof
Newcastle United: Jamaal Lascelles, Jamal Lewis, John Ruddy, Callum Wilson
Nottingham Forest: Wayne Hennessey, Harry Toffolo
Sunderland: N/A
Tottenham Hotspur: Fraser Forster, Sergio Reguilon, Alfie Whiteman
West Ham: Michail Antonio*, Vladimir Coufal, Aaron Cresswell, Lukasz Fabianski, Danny Ings
Wolves: Craig Dawson, Nelson Semedo
* Antonio has not played since breaking his leg in a serious car accident in December. West Ham said in June he would be listed as a free transfer for the purposes of Premier League procedure and his "unique situation" meant no formal decision would be made until the time was "right and appropriate".
Which players are leaving big European clubs on free transfers?
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Jonathan David scored seven goals in 10 Champions League matches for Lille last season
Below are the players leaving clubs who qualified for European competition in Spain, Italy, Germany, and France.
Spanish La Liga
Atletico Madrid: Cesar Azpilicueta, Reinildo, Axel Witsel
Athletic Club: N/A
Barcelona: Wojciech Szczesny
Celta Vigo: Alfon Gonzales, Vicente Guaita, Jailson, Javier Manquillo
Real Betis: N/A
Real Madrid: Luka Modric, Lucas Vasquez, Jesus Vallejo
Villarreal: Raul Albiol, Eric Bailly, Kiko Femenia
Italian Serie A
Atalanta: Juan Cuadrado, Mario Pasalic
Bologna: Andri Fannar Baldursson
Fiorentina: N/A
Juventus: N/A
Inter: Marko Arnautovic
Napoli: Nikita Contini, Claudio Turi, Frank Zambo-Anguissa
Roma: Renato Marin
German Bundesliga
Bayer Leverkusen: N/A
Bayern Munich: Thomas Muller (will complete the Fifa Club World Cup before leaving), Sven Ulreich
Borussia Dortmund: Marcel Lotka
Frankfurt: N/A
Freiburg: N/A
Mainz: N/A
French Ligue 1
Lille: Jonathan David, Ismaili, Vito Mannone, Samuel Umtiti
Lyon: Alexandre Lacazette, Nicolas Tagliafico
Marseille: Chancel Mbemba
Monaco: N/A
Nice: N/A
Paris St-Germain: N/A
Strasbourg: Thomas Delaine
AC Milan have not qualified for European competition, and will allow striker Luka Jovic and defender Alessandro Florenzi to leave on free transfers.
Elsewhere, central defender Olivier Boscagli will leave PSV, while highly rated teenage winger Roony Bardghji will leave Copenhagen, and former QPR full-back Braight Osayi-Samuel's time at Fenerbahce will end.
Which Scottish Premiership players will be free agents on 1 July?
Some Scottish Premiership contracts expire on 31 May rather than 30 June - the below players either already are or will become free agents.
Aberdeen: Tom Ritchie
Celtic: Greg Taylor
Dundee: Scott Fraser, Antonio Portales, Joe Shaughnessy
Dundee United: David Babunksi, Allan Campbell, Lewis Moult, Bryan Mwangi
Falkirk: Russ Munro (will join Inverness)
Hearts: Jorge Grant, Barrie McKay, Lawrence Shankland
Hibernian: Maksymilian Boruc, Junior Hoilett
Kilmarnock: Kyle Magennis, Kieran O'Hara, Kyle Vassell
Livingston: N/A
Motherwell: Moses Ebiye, Harry Paton, Dominic Thompson, Davor Zdravkovski
Rangers: Adam Devine, Tom Lawrence, Ianis Hagi
St. Mirren: Dennis Adeniran, Elvis Bwomono
Image source, Getty Images
Scotland international Greg Taylor is leaving Celtic after they re-signed Kieran Tierney on a free transfer from Arsenal
Free agency is much more common in the lower leagues of English football than at the elite level.
With greater economic insecurity, offering shorter-term contracts means clubs are less likely to be weighed down by a big squad of players on expensive contracts if results take a downturn or relegation befalls them.
In some cases, clubs can have more than a half a squad leave upon expiry of their contracts in a given summer.
Some of the most prominent EFL players set to become free agents are:
Championship: Rhian Brewster (Sheffield United), Aaron Connolly (Milwall), Grady Diangana (West Brom), Anfernee Dijksteel (Middlesbrough), Tyrhys Dolan (Blackburn), Lynden Gooch (Stoke City), Angus Gunn (Norwich), Kenneth Paal (QPR), Emil Riis (Preston), Mark Sykes (Bristol City), Jamie Vardy (Leicester), Kyle Walker-Peters (Southampton)
League One: Will Collar (Stockport), Michael Craig (Reading), Tarique Fosu (Northampton), Charlie Goode (Stevenage), Tyreece John-Jules (Crawley), Josh Koroma (Huddersfield), Hakeem Odoffin (Rotherham United), Josh Onomah (Blackpool), Donovan Pines (Barnsley), Christy Pym (Mansfield), Steven Sessegnon (Wigan)
League Two: Ryan Broom (Fleetwood), George Cox (Swindon), Matty Daly (Harrogate), Janoi Donacien (Chesterfield), Paul Dummett (Carlisle), Mandela Egbo (Colchester), Scott Hogan (MK Dons), Shane McLoughlin (Newport), Tyler Miller (Notts County), Theo Vassell (Barrow), Zac Williams (Crewe), Connor Wood (Tranmere)
Image source, Getty Images
Kyle Walker-Peters looks during Southampton's Premier League match against Fulham at St. Mary's
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