Some viral content goes viral because it fascinates us one way or another -- because it's weird, unsolvable, or controversial. Instances like these -- Rachel Dolezal, that dang dress, or Gangnam Style -- are more like lightning strikes than campaigns. But for content marketers, viral content can still be sought after. Pursuing viral content means you're invested in content that's purely shareable -- content that's likely to get retweeted, liked, and commented on. As this infographic shows us, viral content is more likely to be useful, lengthy, and positivity-oriented. Taken together, we have a picture of content that inspires people as well as makes them think (with a little help from great images and influencer shares).