What's the difference in stock, oversellable and static stock?

Stock balances for different types of SKUs

In stock - Current inventory balance 

Oversellable - If you want to sell a product that's not in stock. E.g the product isn't in stock but you still want to sell it in your shop with a longer delivery time.

Static Stock -Static inventory balance on products that aren't in stock. E.g you sell cakes and you always know you can make 10 pieces so you set static stock to 10.