Inventory Management

From your control panel Products > Settings > Inventory you can change the following settings:

Manage StockYes/ NoIf set to "Yes" it decreases the number of products in stock when purchased.

If you don't need to keep track of available stock (for example digital or downloadable products) you can set it to "No".
Low Stock Tab Threshold1(by default)You can set the number for when a product appears in your Low Stock Tab within your Product List.
Minimum Qty Allowed in Shopping CartYou can set a minimum quantity of a product which the customer has to add to the cart. This minimum quantity is per item in the cart, not for the whole cart!
Maximum Qty Allowed in Shopping Cart10000 (by default)This is the maximum number of items that customers can add to the cart.
Backorders-No Backorders.
-Allow Qty Below 0.
-Allow Qty Below 0 and Notify Customer.
-No Backorders: Customers can't purchase out of stock products.
-Allow Qty Below 0: Customers can purchase out of stock items.
-Notify: Customer will see a message upon checkout that this is a backorder.
Qty for Item's Status to Become Out of Stock0 (by default)By default, when the quantity of a product becomes zero, its stock availability automatically changes to Out of Stock.
Only X left Threshold0This will show "Only X left" where X is the number you put into this setting
Enable Qty IncrementsYes/ NoIf you set this option to "Yes", a field for "Qty Increments" appears to enter the number for the increments. If you enter 5, your customers need to order 5, 10, etc. units of a product.
Enable Customer Group Qty IncrementsYes/NoIf you set this option to "Yes", "Qty Increments" can be set for each customer group on products.
Automatically Return Credit Memo Item to StockYes/NoIf set to "No" you will need to check a box within a Credit Memo to return a product to stock. Otherwise it will do this automatically when set to "Yes".