SKU - Stock Keeping Unit
A Stock Keeping Unit is a unique alphanumeric code assigned to any product that uniquely identifies it. The assignment of code is usually done at the merchant level which helps them to track its inventory or product availability. They are often used to identify different varieties of the same product.
These code are usually not shown to the customers, but to merchants only. SKU Code is usually marked in some particular manner to make the product get identified easily.
For example :
In a Garment Store, an SKU of a particular Jeans is 6212-34. So, the first part before the dash signifies the style 6212 and the part after the dash signifies the size of Jeans.