1. A system of advertising, comprising: an on-line system for sellers of future advertising space to create advertising contracts; an on-line system for presenting the advertising contracts to purchasers of advertising space; an on-line system for the purchasers of future advertising space to select the sellers' advertising contracts; a system to integrate purchased advertising contracts to a delivery mechanism that displays purchasers' advertising in the sellers advertising space; and a system for transferring funds from the purchasers to the sellers on purchase and after completion and audit of the advertising contracts.