According to a recent report by Twitter, nearly 23 million of Twitter's 271 million active users (MAUs) are "bots".
Twitter bots are computer programmes that tweet of their own accord. Twitter says that these accounts are not necessarily spam accounts, which according to the company make up less than 5% of MAUs. Bots are set up by humans but once functional don’t usually have any humans behind them. This affects advertisers who are interested in reaching potential customers.