A keypad lets people without a remote open an automated gate by typing a PIN code. The keypad sits on a post next to the pedestrian gate or driveway entry, wired into the gate motor's command input. Most controllers store 50 to 1000 codes and let you set time-of-day rules (cleaner code only between 8am and 4pm Wednesdays, for example).
Wired keypads run a 4-core cable to the gate motor. Wireless keypads run on a battery and pair to the motor receiver by radio, which saves cable runs but means battery changes every 1 to 3 years.
For commercial sites, swap the keypad for a card reader, fob reader, or fingerprint reader. The wiring and command logic are identical; only the credential type changes.