Photo Credit: http://www.flickr.com/photos/catorze/6738714533/sizes/n/

Many hotels use magnetic cards instead of room keys.

At the end of your stay at a hotel, do not return the magnetic key-card.

Take the key-card with you, and destroy it at the earliest opportunity.

The magnetic key-card contains all the information you gave the hotel: your address, your credit card number, the expiry date of your credit card, etc.

Anyone with a card reader (an inexpensive device, easy to find at any computer store), could access that information easily.

Make sure to take note of this information.

Dahan Binyamin is the Cellular Phone Section Chief in the Israeli Police