An envelope closer is a device used to secure the opening of an envelope. It typically consists of a CLASP, FLAP, and SEAL. The CLASP is a metal or plastic fastener that is used to hold the envelope closed. The FLAP is a piece of paper or fabric that is folded over the opening of the envelope and tucked into the CLASP. The SEAL is a wax or adhesive material that is applied to the FLAP to ensure that the envelope remains securely closed.