If you have been around social media marketing for any amount of time, you have heard the term “link bait.” It’s a great way to gain traffic, readership, and rankings — but what actually is it?

Link bait refers to something that grabs the attention of the blogosphere and makes people want to link to it from their blogs or tell their friends about it. It really can be just about anything, however, some link bait does better than others.

Two approaches that always seem to do well are controversy and humor.

The more simple piece to write, of course, is controversy link bait. Write something that a lot of people disagree with and you’re going to be talked about. Jason Calacanis is a master of this kind of link baiting. In my opinion you have to be careful how you use this tactic, as you can burn bridges much faster than you can build them.

Humor is a different animal. When you are trying to write a funny piece of linkbait, using humor you actually have to be funny — or at least more than just mildly amusing. I saw a great piece of humor link bait recently from Jane Copland and Rand Fishkin of SEOmoz: Google Search Results Missing from OneBox. I loved the search for “things rick astley would never do.” It was rather clever and funny. Now if only Google would actually return those mock results!

Other ways to bait for links include — tools (like blog plugins and browser addons), late-breaking news and scoops, original research, and photos that you’ve Creative Commons licensed.