My RSS feeds have been buzzing about the LinkedIn faceted search since it was first released from beta in December. So why is the new search at LinkedIn so interesting that people are almost constantly discussing it? I think it’s partly because LinkedIn is a site that is used by most professionals and searching for people is core functionality on LinkedIn. But the search interface on LinkedIn is also a very good example of faceted search.

I decided to have a closer look into their search. The first thing I realized was just how many different kinds of searches there are on LinkedIn. Not only the obvious people search but also, job, news, forum, group, company, address book, answers and reference search. LinkedIn has managed to integrate search so that it’s the natural way of finding information on the site. People search is the most prominent search functionality but not the only one.

I’ve seen several different people search implementations and they often have a tendency to work more or less like phone books. If you know the name you type it and get the number. And if you’re lucky you can also get the name if you only have the number. There is seldom anyway to search for people with a certain competence or from a geographic area. LinkedIn sets a good example of how searching for people could and should work.

LinkedIn has taken careful consideration of their users; What information they are looking for, how they want it presented and how they need to filter searches in order to find the right people. The details that I personally like are the possibility to search within filters for matching options (I worked on a similar solution last year) and how different filters are displayed (or at least in different order) depending on what query the user types. If you want to know more about how the faceted search at LinkedIn was designed, check out the blog post by Sara Alpern.

But LinkedIn is not only interesting because of the good search experience. It’s also interesting from a technical perspective. The LinkedIn search is built on open source so they have developed everything themselves. For those of you interested in the technology behind the new LinkedIn search I recommend “LinkedIn search a look beneath the hood”, by Daniel Tunkelang where he links to a presentation by John Wang search architect at LinkedIn.