1. A system of a mobile device, Alpha, and a mobile device, Beta; where Alpha is controlled by a first user; where Beta is controlled by a second user; where the first user and the second user are different persons; where Alpha shows a first image; where Alpha makes a data containing an Universal Resource Locator (URL) of the first image; where the data furthermore contains an electronic address of the first user; where Alpha displays the data in a barcode as a second image; where Beta has a camera; where Beta scans the barcode with the camera to obtain an image Phi; where Beta decodes Phi to extract the data; where Beta sends an electronic message to the electronic address of the first user; where the electronic message contains an electronic address of the second user.
1. A system of a mobile device, Alpha, and a mobile device, Beta; where Alpha is controlled by a first user; where Beta is controlled by a second user; where the first user and the second user are different persons; where Alpha shows a first image; where Alpha makes a data containing an Universal Resource Locator (URL) of the first image; where the data furthermore contains an electronic address of the first user; where Alpha displays the data in a barcode as a second image; where Beta has a camera; where Beta scans the barcode with the camera to obtain an image Phi; where Beta decodes Phi to extract the data; where Beta sends an electronic message to the electronic address of the first user; where the electronic message contains an electronic address of the second user. 4. The system of claim 1 , where the first image depicts a product or service for sale.