Rich snippets are all the rage these days. Ever since Google started enhancing their search results with these extra tidbits of information, everyone is rushing to update their web sites with the metadata to enable them. So what is the benefit of having a “rich” search result for your site? Good question. Other than giving the search engine user a little bit of extra bit of detail, I suppose there’s also a subtle psychological factor that kicks in. Someone might be more inclined to click on a search engine result that has a 5 star rating and a friendly face than one that doesn’t. Plus, they’re just plain cool. Who doesn’t want to add bling to their search results? But this only scratches the surface. There’s much much more to them than that.
Rich Snippets, as Google calls them, are actually semantic markup. The idea of marking up some sort of document with meta information for the benefit of machines is not a new idea. Semantic markup is as old as information technology its self. For example, a Word document contains metadata about its author, and a digital photo contains meta data about the camera it was taken with. You might, for instance, store your digital snapshots in a photo archiving program which uses this semantic data to filter your photos by date taken, lens type, flash used, etc. So, in essence, metadata is data about data.
It’s should be clear, then, how this “data about data” can be extremely useful to search engines. It can provide a search engine the ability to derive a semantic meaning from a document’s meta information rather than having to rely purely on the abstract, human understandable, concepts within the text of the document. Searches can become less about keywords in text documents and more about relationships between semantical data types.
To illustrate this point further, consider the following search: Find all restaurants with a 3.5 star or better rating on the Las Vegas strip that specialize in Italian OR Mexican cuisine AND are open after 11 PM on Sunday nights AND do NOT require reservations. On the semantic web, rather than a list of links to restaurant web sites that may or may not match your given criteria, you might get a list of “restaurant result objects” that DO match exactly that criteria and never even have to visit the restaurant’s web site. This is where the real power of semantic data lies. Instant information aggregation.
This “semantic web”, also, is not a new idea. In fact, Tim Berners-Lee himself envisioned the world wide web as a kind of “Semantic Network Model” and even the earliest HTML specifications included the concept of meta tags, which you are undoubtedly familiar with. Later iterations, such as XHTML, took this idea a step further. Most notably is the RDFa specification, which has been around for quite some time.