What: Klout measures the influence of Twitter accounts by giving a score of between 0 and 100. Higher "Klout" numbers represent an account with a wide and strong sphere of influence.
The media measurement tool is free for most users. A paid premium version might launch this fall.
How: Klout uses more than 25 different variables broken down into three categories: true reach (engaged followers vs. spam bots, dead accounts, and so on); amplification probability (likelihood a message will be retweeted or spark a conversation); and network influence (determined by looking at the influence, or Klout scores, of people who are followers of the Twitter account.)
Len Kendall, digital account supervisor at GolinHarris, says, "We use it mostly for specific client campaigns when we need to identify influencers. Klout score is one of the variables we consider in terms of who we reach out to and keep our radar on."
Why: In addition to identifying influencers online, PR firms use Klout to measure the success of the Twitter accounts they manage on their clients' behalf.
"If we see a meaningful drop in a Klout score, we can look into the account, see what's not going right, and provide direction," says Callan Green, social media account executive at San Diego-based marketing firm Bailey Gardiner.
Klout also provides a content analysis of the topics a user talks most about on his or her Twitter account. "Generally, when we start with a client, we have a strategy of what they should talk about," adds Green. "We want to be sure those two things match up."
Who: Kendall suggests PR firms have a lot to gain by using Klout. "In terms of visibility and accuracy, Klout seems to be the Google of Twitter measurement tools," he says. "It is an easy way to filter through the masses."
Clients who have heavily invested in Twitter as a communication channel should also consider using it, advises Green. "It really depends how in-depth they want to go with their reporting."