We investigate the rapidly expanding world of social networks, and give you the lowdown on their pros and cons so you can decide which to hitch and which to ditch.

There are social networks for everyone and everything. Whether you want to exploit colleagues for connections, take faux-retro pictures on your iPhone, or brag about how far you ran, there’s a network for that. In fact, social networks are so prevalent that the term has almost come to mean nothing at all. We decided it was time to take a look at some of the biggest contenders and see where they soar and where they sink.

Facebook: Everyone

Facebook’s most recent update (as of press time) introduced a ticker of friends’ activity to the news Feed.

Saying “everyone knows about Facebook” isn’t even hyperbole anymore. Of the world’s 7 billion people, over 750 million of them are on Facebook. It’s all encompassing, your friends are already on it, and it doesn’t even have spam. But not all is rosy. Every few months Facebook irritates its users with an overhaul. They almost always improve functionality, but frequently leave users wondering where things are. The more serious issue, however, comes along just about as frequently when legitimate privacy concerns are made public. But it seems Facebook is too big to fail, and no matter how many times they sell our information and exploit our so- called privacy, safe money says they’ll be around for a long, long time.

Twitter: The Celebrity

Everyone from your favorite band (radiohead) to your favorite magazine (Mac|Life) is on Twitter.

Twitter is the easiest way to keep up with your favorite celebrities, bands, and friends, and learn breaking news as it happens. The streamlined 140-character blips make a trip to Twitter an effective way of knowing what’s happening in the world as quickly as possible. In fact, people have reported reading about earthquakes before they even feel them through the magic of Twitter.

Unfortunately, it’s also the king of spam networks, with scammers, phishers, and pornographic accounts coming out of the woodwork to “follow” and tweet users who use any sort of hot words like “iPhone 5,” “Apple,” and “Steve Jobs.” Yeah, we’re telling you from firsthand experience.

Google+: The Revolutionary

Another awesome feature of Google+? Animated GIFs work perfectly.

Google+ stripped away all the nonsense Facebook keeps adding, and substituted genuine, awesome functionality. On the first day, beta users were taking part in “hangouts” that allowed viewers to videochat with up to 10 people, and placing friends in “circles,” an intuitive way to organize contacts into tiers that determined custom privacy settings.

Facebook responded quickly, implementing their own new take on privacy settings and announcing a partnership with Skype for videochatting. Google+ remained “invite only” for almost three months. In that time, Google lost much of their momentum and plenty of users returned to Facebook. Just before Google+ came out of beta, a study by Bime Analytics found that 83 percent of current Google+ accounts were inactive.

Tumblr: The Artist

Using the Tumblr dashboard, you never have to actually visit any of the sites Tumblr hosts.

Technically Tumblr is a microblogging site, not a social network, but the line is blurred. In more ways than one, Tumblr is the MySpace of the current age-- users create their own profile (which just so happens to be a website in this case), show off cool music, pictures, or whatever they want. The focus on creating and sharing content is what differentiates it from the pack, and the streamlined dashboard allows you to check posts quickly.

LinkedIn: The Opportunist

Our favorite feature of LinkedIn is also one of its most depressing.

LinkedIn is the unabashed Facebook clone for the workplace. Instead of “friends,” you have “connections,” and a larger connection base puts you in contact with more professionals. In place of uploading photo galleries, you can upload your résumé and even seek recommendations from coworkers. LinkedIn also has a small box that allows you to see who’s viewed your profile, which gives frequent users of the site a measure of the impact of their tinkering.

Diaspora: The Conspiracy Theorist

Diaspora’s banner proves we’re not in Facebook anymore.

Diaspora is still in private alpha, but the upcoming open-source social network has gotten much press for having its head in the right place. Its current landing page touts three things: choice, including connection sorting that could rival the circles in Google+; ownership, which makes it perfectly clear that you own the rights to everything you upload on the site (the opposite of Facebook); and simplicity, which speaks for itself.

Unfortunately, in the time it has taken Diaspora to launch publicly, Google+ has launched, boasting all three of Diaspora’s tent poles. We’re excited to see what Diaspora does when it eventually does launch, but we have a bit of a bad feeling.