A data processing system issuing electronic certificates through "online" networks of personal computers, televisions, or other devices with video monitors or telephones. Each electronic certificate includes transaction data and identification data, and can be printed out on a printing device linked to a consumer's personal input device, or electronically stored in a designated data base until a specified expiration date. The certificate can be used for various purposes, including use as a coupon for a discounted price on a product or service, proof of a gift or award, proof of reservation, or proof of payment. Consumers access the data processing system online, browse among their choices, and make their selections. The data processing system provides reports on the selected certificates and their use following selection. Certificate issuers also have online access to the data processing system and can create or revise offers, and provide various instructions pertaining to the certificates, including limitations as to the number of certificates to be issued in total and to each individual consumer.