Zippo lighters date back to 1932 and are recognizable for their trademark design and quality. However, many fake imitations exist both online and offline due to Zippo's popularity. There are several ways to determine if a Zippo lighter is authentic, including checking for the bottom stamp with serial number and place of manufacture, ensuring the hinge stops at a 45 degree angle rather than laying flat, and listening for the distinctive sound made when opening the lid. Authentic Zippos also come with a lifetime warranty and are only available from authorized retailers.