What is the difference between programmatic and direct?

Programmatic advertising is the process of buying and selling online advertising space through real-time bidding. This means that ad space is bought and sold on an impression-by-impression basis, with advertisers and publishers using automated systems to buy and sell ad space. Direct advertising is the process of buying and selling ad space without the use of an automated system. This means that ad space is bought and sold through negotiations between advertisers and publishers.