Information architecture is one of the most important user experience elements of a website because it directly affects navigation, often affects URL structure, and it is important to both SEO and conversion optimization. On ecommerce websites, product “merchandising” may impact aspects of information architecture. To ensure that users can find the information they are looking for as quickly and as easily as possible, it is important to understand the technical differences between categories and attributes.
Attributes
Attributes are a form of description which outline the properties of an object (a product, a blog post, a user, etc.). An attribute defines an objective feature or quality regarded as a characteristic or inherent part of an object. Generally attributes are immutable, meaning they do not change over time. However, there are some attributes, such as a product’s rating or price, that may change over time. A single item may have a number of different attributes, but generally each item will have only one value for each attribute.
Tip: Attributes are generally adjectives.
Not all attributes need to be visible to a user, however attributes that are displayed may be combined with special markup and other technology to provide relevant information to search robots, crawlers, and assistive technology. This information can be used to enhance search results and provide a superior user experience. For example, attributes allow items to be easily compared, and because attributes may represent values on a range, attributes can be used to easily filter a large collection of items. This helps users quickly locate items that meet a specified criteria.
A t-shirt has a size, color, and style (and many other attributes like price, manufacturer, material, and rating). A consumer may want to compare price and rating for black, v-neck t-shirts that are either small or medium. Through the use of attributes, these types of complex filters and comparisons are made possible. The more accurately an object is described through attributes, the easier it will be to search, sort, or filter the object.
Categories
Categories are a form of classification, or grouping, according to shared qualities or characteristics. Categories (sometimes referred to as “collections”) are subjective collections of items that may be curated manually or automatically based on a set of predefined rules. Categorization is subject to change over time and may be hierarchical, meaning that each category may have sub-classifications that allow a collection of items to be further refined. Objects may also exist simultaneously in any number of categories.
Tip: Categories are generally nouns.
Categorization is heavily reliant upon marketing and merchandising and often defines a website’s URL structure and navigation, therefor it has a pronounced impact on both user experience and SEO.
Crossover
On ecommerce sites, it is common for an important attribute value to also be used as a category; this may happen if an attribute is particularly popular, necessary in navigation or SEO, or is essential to marketing. Generally when attributes must be surfaced as categories, it is best to automate the categorization with rules so that the overhead of catalog maintenance remains low.
It may be helpful to think of categories as shelves, drawers or containers to place items inside of. Moving an item from one container to another does not change the qualities of the object itself (it’s attributes), but it does change it’s classification (category).
Going back to our previous t-shirt example, a v-neck t-shirt may be included in a “Featured” category which highlights items that are highly valued by customers or business objectives; this type of category would not need to rely on an attribute because being “featured” is not an objective quality of the t-shirt itself, instead it is a subjective grouping. The same v-neck t-shirt may also appear in a “V-necks” category that is populated automatically with all the available v-neck t-shirts. This “promotion” of the style attribute will allow visitors to locate the item, and other similar items more quickly particularly if the category is featured prominently in navigation, and by appearing in search results.