As a front-end web developer, I often hear the terms “findable”, “searchable”, “indexable” and “accessible” thrown around interchangeably. For many, they mean that the content can be accessed by a non-human, be it a screen reader or a search engine spider. On some level this is true, but there are several significant differences that are must not be overlooked.

For the sake of this discussion:

• Findable: how easily a site can be found when using a search engine (rankings). Yes, I realize that this term also refers to how easily content can be found once the user is on the site, but I’m ignoring that aspect of it for now…
• Searchable: how easily specific content within a site can be accessed when using a search engine (deep-linking)
• Indexable: how easily the content of a site may be retrieved and used in search engine results
• Accessible using AT: how easily someone using assistive technologies can use your site

(ShoeMoney.com has compiled a list of definitions for SEO from some industry experts, as well)

A site created completely in Flash or Flex may be findable thanks to the use of meta-data, but it is not indexable. With some diligent coding, information may be searchable, but this is no guarantee that it will be accessible.

(Not content with these descriptions? Have more to add? Please let me know what you think in the comments!)

As I’ve mentioned, my background is in accessibility: prior to coming to Resource, I worked on large subscription-based web applications. SEO was not a consideration at all. However, accessibility was. When I first came to Resource, I was eager to see how the two complemented and contrasted each other.

Overall, I see some overlap between the areas. However, their focus is different.

SEO is based on a page mentality - this is apparent in the search results that come up. Many common SEO techniques are applied at the page level, via adding meta tags or optimizing title tags. This is how a site that requires login, or is built using a technology like Flash or Flex, can appear in search results. A search engine can access meta information about the page, and use that to rank it. Findability relates to the notion of the discovery of the page itself.

A secondary notion is that of searchability. A web application may be found on google, but can the specific content that is being sought be retrieved? Searchability refers to the idea that site visitor can easily navigate to the specific information he’s searching for within the site, once the site itself has been discovered.

Both searchability and indexability deal with how elements of the page can be accessed, but arguably in different directions. Deeplinking into a flash movie may facilitate searchability, helping a site visitor dig into the site at a specific point. In contrast, indexability refers to the ability of a search engine spider to do a broad pull of content from the site.

Where SEO and Accessibility really start to diverge is when we move beyond the retrieval of content itself. A search engine spider is only interested in the data, so that the appropriate search result may be returned to an information seeker. In contrast, accessibility refers to the ability of a site visitor to navigate within an experience. The implications are significant: each interaction must be coded in a way such that a screen reader user can activate the change, and be notified of any changes that occur.

Another important distinction is the extent to which the site content is made available. A site may work to optimize or only make indexable certain aspects of the site. In contrast, accessibility refers to the ability of all content to be available and able to be engaged with.