Biochip technology allows for thousands of biological reactions to be performed simultaneously on a solid substrate the size of a fingernail. A biochip implant system consists of a transponder implanted beneath the skin which contains an identification number, and a reader which activates the transponder and receives the ID number. Biochips have applications in animal tracking, e-commerce, passports, medical diagnostics, and other areas due to their ability to store personal data, though they also raise privacy concerns if implanted without consent.