An attribute is just what it sounds like, an attribute or feature of your product. Unlike variations, however, attributes are non-variable features. For example, if you sell T-shirts, an attribute might be "100% cotton" or "Pre-Shrunk". You will first create attribute sets, such as "Material" and "Features", and then you can assign particular attributes to each set. This make it easier to highlight certain features of your product, as well as making it more convenient to enter product descriptions if many of your products have the same attributes. Here's an example of how attributes will appear on your site:
To set up an attribute set navigate to the "Catalog" tab, and then click "Attributes". Click on the "Add" button and name your attribute set. Once it’s named, click next and you can add different attributes to the set. To do this, just click on the "Add New Attribute" button and fill out the form. If you would like more than one value for each attribute, just click the "Add a Value" button until you have the required number of values. Repeat until you are satisfied with your attribute set. Once your attribute set is set up, click the "Set Category" button to assign the attribute set to the categories you would like to associate it with. Just repeat the process until you have all of the attribute sets that you need.