[Question] What is SDK?

Hi, i wanna know what is SDK
I saw some black squad script with "SDK" in the title...
It look interesting, to hack on some games.
But what is SDK? How do use this thing.

Waiting for a answer. Thank's

SDK is a "Software-Development Kit". A bunch of classes usually auto-generated or reversed by a hacker to provide easier understanding of the game's internal architecture and allow you to use these pre-reversed classes to create a cheat without having to reverse and create all those classes yourself.

In a nutshell it makes making cheats easier.