When a passenger arrives at the port to check in to the cruise line, he or she will receive a key card which will serve as the room key, charge card for anything he or she buys on the ship (like drinks, souvenir) . The key card is also a pass to get on and off ship in each port.
When a passenger first boards the ship the security personnel will have him insert the key card into a scanner and then will take a photo that is included in the magnetic strip on the card. Each time he or she gets off ship they will need this key card and many times also a photo ID (passport or driver’s license). This card allows the cruise liner to keep an accurate track of all passengers entering and/or leaving the ship.