The January transfer window means something different to each club.
For the bigger clubs, it represents a time to reinforce their squads for the latter stages of league title run-ins and European knockout rounds. For smaller teams, signing new players takes a back-seat to securing what they already have for another five months.
Celtic fall somewhere in the middle of the two.
Certainly, the January window denotes a time to enhance the current squad. But given the club's transfer policy of signing young and selling for a profit, it has also become a time to ensure no big players leave mid-season.
This time around could see stalwarts Joe Ledley and Georgios Samaras urged out the door at Parkhead if talks over new contracts for the pair do not bear fruit.
But, traditionally, the January window has proven a shrewd time to bring in new players for the Bhoys.
From short-term signings like Craig Bellamy in 2005, to more recent examples in tune with the new transfer policy such as Ki Sung-Yueng in 2010, January has been a good mistress to Celtic.
Neither Bellamy nor Ki make the list, but read on as we take a look at the five best January signings the club have made in the past 10 years, as adjudged by price tag and overall contribution to the team during their time in the Hoops.