Transfers happen for a variety of reasons; the player is unhappy, the club needs the money etc. However, one of the main factors behind a swathe of moves this summer is simple - the player has simply outgrown their current home.
Planet Sport takes a look at some big moves this summer which are coming around simply because the player has become too big for his club.
Kylian Mbappe - Paris Saint-Germain
Mbappe is the most wanted player in the world - and he has a big decision to make this summer.
Current club Paris Saint-Germain are working hard to persuade him to stay, even on a deal of just two years with the promise of being the highest paid player on the planet.
But what does Mbappe gain from staying in Paris? Many believe he has outgrown the French champions and the logical move would be to Real Madrid.
Erling Haaland - Borussia Dortmund
Despite only being 21, the British-born Norwegian superstar is one of football's hottest properties.
His career to date has been planned precisely. From Red Bull Salzburg to Borussia Dortmund, his clubs have been chosen carefully.
There is little doubt as one of the world's best strikers, he is too big for Dortmund. Now he is ready for his next move.
Declan Rice - West Ham United
West Ham fans believe that Declan Rice is just fine where he is and he has played a huge part in turning them into top-four contenders.
But let's be realistic. Rice is one of Europe's most in-demand players and West Ham know they can't afford to give him the contract he deserves.
The fact he is likely to quadruple his wages with a switch, only confirms that the time is right for Rice to move on. Manchester City, Manchester United and Chelsea are all ready to make a move this summer.
Raphinha - Leeds United
The Brazilian winger has been outstanding for Leeds since his arrival from French outfit Rennes.
Strongly linked with Paris Saint-Germain and Barcelona, it is hard to see him staying at Elland Road beyond this summer - even if Leeds stay up.
Raphinha has a lot of competition to make Brazil's World Cup squad and he needs a move to secure his place in Qatar.
Aurelien Tchouameni - Monaco
The Monaco midfielder has emerged as one of Europe's top young performers in the last 12 months.
Chelsea tried to sign him last summer, but now the likes of Real Madrid and Liverpool are hot on his trail.
Tchouameni is a key part of Didier Deschamps' French side and it is safe to see he is ready to leave Monte Carlo.
Harry Kane - Tottenham
The England captain faces the prospect of ending his career without challenging for domestic titles.
It is not that hard to argue that Harry Kane has outgrown Tottenham - he did so some time ago, but will he do anything about it?
Spurs stopped him joining Manchester City last summer and it remains to be seen if they, or anyone else will try and land him again.
Darwin Nunez - Benfica
The Uruguay striking sensation is being linked to a host of clubs with Manchester United understood to be heading the chase for the Benfica star.
Nunez has seen Luis Diaz prove a revelation after departing the Portuguese league for the Premier League.
Now Nunez believes the time is right to move on after outgrowing the Estadio Da Luz.
Antony - Ajax
One of Ajax's star men and among a handful of players you could argue have outgrown the Dutch giants.
Antony has been outstanding under Erik ten Hag but like his manager, he may well feel the time is right for him to move on.
Like Raphinha, a World Cup place will be on his mind and a big move could help cement it.
Julian Alvarez - River Plate
A bit of a cheat this one. The Argentine international is showing himself as one of the best talents in South American football.
He clearly looks like he is too big for River and he agrees too. That is why he has already agreed a move to Manchester City in the summer.