Sometimes using a nonstick baking sheet is not enough when cooking items that stick well, such as macarons or coconut tuiles for example.
In this case it's possible to line the sheet with cooking parchment,but one can also use a silicone baking mat which is a flexible sheet with a silicone coating, more non-stick than any baking sheet. Nothing sticks to it, and above all can be reused after washing.
If you intend to buy:
Get one the size of your oven for the most efficient use.