Colour correcting isn't technically a new trend or beauty trick in the industry—it had its heyday back in the 1990s when makeup artists swore by its efficacy in correcting skintones for an even finish. The main purpose of colour correctors is to reduce or provide coverage over a certain colour on your face (think dark spots or redness)—all you need to do is use a colour that sits at the opposite end of it on a colour wheel. A colour corrector doesn't actually replace a concealer or foundation, but it's the base that neutralises uneven skintones before applying both.
In a nutshell, these are the colours to go for according to your skin dilemma:
1) Yellow: any purple, blue undertone eye circles, dullness
2) Orange/Red: dark circles on skintones that are medium/olive
3) Green: redness
4) Blue/Purple: sallowness, yellow-tinged skintone
A tip is to only use these correctors on specific spots or areas over your face instead of entirely changing your shade of skintone from warm to cool or vice versa. You wouldn't want your face to sport a completely different skintone than your neck or shoulders (oh, the horrors!) A little goes a long way with these, so a light drop/dab will work wonders and especially for a natural finish.
Below, seven colour correctors that can neutralise colour irregularities in a jiffy: