Loan deals are a way of giving a player a chance to prove himself, while also allowing the parent club to not have to worry about selling him immediately.
As a whole, most moves don't work out for the better, with loan players often put to one side in favour of others. However, for a few lucky players, last season's loan deals actually benefited their career in the long-term.
Let's take a look at nine such players...
9. Javier Manquillo
Transfer: Atletico Madrid to Sunderland
The 2016/17 season was a dismal one for Sunderland, who, after years of flirting with relegation, finally dropped down to the Championship. Javi Manquillo, who spent the year on Wearside on loan from Atletico Madrid made a good showing for himself though.
The Spanish full back featured 20 times in the Premier League and was far more convincing than a similar loan spell at Liverpool. With his reputation intact he stayed in the north east (and in the top flight), signing a three year deal with Newcastle United.
8. Federico Fazio
Transfer: Tottenham Hotspur to Roma
Federico Fazio could not have looked more out of place in the Premier League if he tried, with Spurs' experiment of deploying the Argentinian centre-back an outright failure, prompting an underwhelming temporary return to Sevilla.
Desperate to shift him out again prior to last season, Spurs somehow convinced Roma to take the 30-year-old on board but it proved a ingenious decision with Fazio finishing the campaign as a key player for the Serie A side, before signing permanently this summer.
7. Bruno Martins Indi
Transfer: FC Porto to Stoke City
Having failed to establish himself as an automatic starter in the Primeira Liga, Dutch international centre-back Bruno Martins Indi opted to join Stoke City on loan for the entirety of the 2016/17 campaign.
The 25-year-old was a rock at the back for the Potters, playing 35 times in the top flight as Mark Hughes' men finished 13th and Stoke City gladly paid up the £7m fee to bring Martins Indi over as a permanent signing this past August.
6. Alvaro Negredo
Transfer: Valencia to Middlesbrough
Middlesbrough's long-awaited return to the top flight saw them bring in former Manchester City striker Alvaro Negredo on loan from Valencia and the Spanish powerhouse was one of the rare shining lights in a disappointing season for Boro, who dropped straight back down.
Nine goals in the Premier League, a third of his side's total tally for the entire campaign, demonstrated Negredo's continued ability in front of goal and Turkish champions Besiktas jumped at the chance to sign him this summer.
5. Bertrand Traore
Transfer: Chelsea to Ajax
Chelsea's extensive loan networking system allowed Burkina Faso striker Bertrand Traore to try his luck in the Eredivise last season, having shown glimpses of his ability for the Blues the previous year.
The 22-year-old was impressive for Ajax, scoring nine times in the league and four more in Europe as they reached the Europa League final. The scramble to sign him permanently this summer ended with Lyon, who paid Chelsea £8.8m for his services.
4. Nabil Bentaleb
Transfer: Tottenham Hotspur to Schalke
After falling completely out-of-favour under Mauricio Pochettino, Nabil Bentaleb was offloaded to Schalke at the start of the last season, with Spurs keen to let the Bundesliga side inherit the sometimes problematic midfielder.
Yet, the Algerian international proved himself in Germany and was a key figure for the Gelsenkirchen-based club. By February already, Schalke had reached an agreement to make the deal permanent for the 22-year-old.
3. Nathan Ake
Transfer: Chelsea to Bournemouth
Bournemouth opted to bring in Dutch youngster Nathan Ake on loan from Chelsea to help solidify their back line ahead of their second season in the Premier League, but even manager Eddie Howe would not have expected the centre-back to be so impactful.
Ake's contribution to the Cherries' success was so great that Chelsea boss Antonio Conte ended the loan deal early in order to have the youngster back in his squad as they closed in on the title. Needless to say, Ake was signed for a club-record £20m this summer.
2. Tammy Abraham
Transfer: Chelsea to Bristol City
Youngster often have a tough time of finding their feet on loan in the Championship, but not Tammy Abraham. The England U21 striker was absolutely phenomenal for Bristol City last season, finishing runner-up in the race for the Golden Boot with 23 goals.
His form helped the Robins avoid relegation and he was duly awarded both the Player and Young Player of the Year awards. Chelsea will be hoping that he can have a similar impact on loan with Swansea City year this year, his first taste of top flight football.
1. Mamadou Sakho
Transfer: Liverpool to Crystal Palace
The French centre-back was a complete outcast on Merseyside due to a poor run of form and off-field problems, but with relegation looming Crystal Palace gambled on loaning the defender midway through last season.
Sakho was immense for the Eagles, shoring up the back as the South London club moved away from the relegation zone to safety. Like many on this list, the move was made permanent this summer.