Attributes are the building blocks of your product catalog, and describe specific characteristics of a product. Product attributes can be organized into attribute sets, which are then used as templates for creating products.
Attributes determine the type of input control that is used for product options, provide additional information for product pages, and are used as search parameters and criteria for layered navigation, product comparison reports, and promotions. You can create as many attributes and attribute sets as necessary to describe the products in your catalog. In addition to the attributes that you can create, system attributes, such as price, are built into the core Magento platform and cannot be changed.