All the current technology has been building up for a literal "mark" of some type to be placed in the right hand or forehead. What form this will take is anybody's guess. A few contenders like a microchip, quantum dot tattoo etc... When it comes it will be clear and will involve the personal decision to worship the antichrist and allegiance to him per Revelation 13:15.
History shows evil things used in the past to claim ownership over another person.
https://www.encyclopedia.com/humanities/applied-and-social-sciences-magazines/branding-slaves