In a world where big numbers mean big business, the size of a celebrity's Twitter following is of great interest to fans and advertisers alike.
But how many of the millions of Twitter users who follow stars such as Lady Gaga and Justin Bieber are real?
Most people with Twitter accounts will have been bombarded with indecipherable messages apparently sent by 'spambots' who don't exist.
And now a British firm claims it may have found a way to root out the fake and fraudulent accounts that make some celebrities' Twitter follower counts artificially high.