Naked shorting is when you sell the underlying stock without borrowing it first. You have 2-3 days from transaction to settlement (depending on the market), so you can enter a transaction at T and then only locate borrow at T+2. Obviously, you're running the risk that you can't find borrow in time.
In most cases, however, you short by checking for available borrow first, and _then_ shorting.
Naked shorting is when you sell the underlying stock without borrowing it first. You have 2-3 days from transaction to settlement (depending on the market), so you can enter a transaction at T and then only locate borrow at T+2. Obviously, you're running the risk that you can't find borrow in time.
In most cases, however, you short by checking for available borrow first, and _then_ shorting.