what is the effect of this pedal? ive watched a thousand video of compressor pedals and i cant figure out what it adds

what im trying to to is to get Gilmour's sound and on his guide it says that he uses a compressor pedal.. so yeah some help would be great

adds sustain, evens out pick attack, COMPRESSES the tone

you should know that when you pick a string, the loudness of the produced sound varies if you pick stronger or lighter. a compressor removes that effect.