Many websites are funded by the sale of advertising and many other companies invest large amounts of money in advertising campaigns hoping to increase revenue in response.
The system relies significantly, on automated exchanges that will match adverts with potential customers. Ad fraud takes advantage of these automated processes to masquerade as real users and take income for displaying adverts to non-existent users. The fraudulent activity affects both advertisers and publishers.
Advertisers are left paying for adverts that are displayed to non-existent users and publishers suffer increased chargebacks, as advertisers start to identify the number of adverts they suspect have been displayed to bots (known as IVT). Ad exchanges will detect levels of IVT and when they are too high, can block sites from accessing the exchange.