You have more than likely heard about LinkedIn. It launched a few years back with a small number of users and now has well over 500 million and probably half those numbers are comprised of unique business users.
Its portal allows you to build your online profile in a very user-friendly way and helps you to find other users profiles quite easily and accurately. You can use it to find people which are related to a business or service, however, most users will use it to find jobs or if you are an employer then likely prospects to fill those positions.
The best thing about LinkedIn is definitely its search engine capabilities. You can effectively search LinkedIn profiles using various criteria which can make it more attractive to business users.
Its profiling is based upon the status of your profile, not the profile itself. What that means is, if you have a big network and a lot of contacts which are connected to your network, you will end up ranking higher in the results of other peoples searches.
You can choose to add people with the bigger networks or those that have the highest number of recommendations. Sadly this feature is well known among the older users and can be manipulated by them in order to bolster their standings artificially. You have to take this into account when using their services. For the most part, though many of its users do not do this sort of thing and so it does not completely render it useless.
The LinkedIn networkers are now beginning to ask how they can make real business use out of LinkedIn and make some money with it. Somewhere in the near future, LinkedIn will have to address that need because there are some competitors trying to address those concerns and if LinkedIn does not rise to the occasion it will only be a matter of time before they find themselves eclipsed and outdated.
However, all that being said LinkedIn is still one of the best and well-known sites for professionals and amateurs to look for work. And is a great resource for building a business online footprint.