Everything about preshot in Valorant
You surely have already seen an opponent suddenly appear in front of you and headshotting you at the speed of light. No need to yell “WALLHACK!”, it’s certainly a preshot. But what is it?
A preshot is an anticipated shot. When you know where the opponent is, or when you are about to peek somewhere they're likely to be, you can pick while firing a small burst at head level.
Even if, most of the time, it will be useless, it will still allow you to regularly catch off guard an enemy well installed, turning their advantage against them. By dint of playing, you will be able to determine in advance where the opponents hide and determine whether preshot is worth it or not.
However, be careful not to abuse it. This can be useful during a rush, but during a calmer game phase, an unnecessary preshot would also reveal your position.