It's called 'shared' and if you type it into script editor you will see it shows up as a built-in function and Roblox doesn't provide any documentation on it. Does anyone know what it is/what it does?
If you open a script and simply type in "shared" it will show up.
shared is a global table that is used to store variants that can be shared between scripts of the same kind.
shared shares the same purpose of _G