A shocking study by the National Associated for Information Destruction has revealed some terrifying information: 40% of electronic devices found on the second-hand market contains personal information. This information includes usernames and passwords, personal information, credit card numbers, and even tax information. Tablets were the most affected, with 50% of them containing this sensitive information, while 44% of hard drives contained the info. What does this mean for you? It means that all of those old devices you have laying around could put you in danger. Deleting…Really Deleting…Your Devices Many of us will haphazardly click the ‘Delete’ button on our devices and think that the information is gone. Unfortunately, that’s not how it works. You might not see it any longer, but that doesn’t mean it doesn’t exist. To really make sure your device is totally clean, you have to fully wipe or destroy the hard drive. However, before you do, make sure to back up your information. Back Up Whether you use a Mac or a PC, there are methods built into your device that will allow you to back it up. You can also use the iCloud for Apple, or the Google Auto Backup service for Androids. And of course you can use external hard drives, thumb drives or remote backup. Wipe Wiping a device refers to completely removing the data. Remember, hitting delete or even reformatting isn’t going to cut it. Instead, you have to do a “factory reset,” and then totally reinstall the OS. There is third party software that can help, such as Active KillDisk for PCs or WipeDrive for Mac. If you are trying to clean a mobile device, do a factory reset, and then use a program like Biancco Mobile, which will wipe both Android and iOS devices. Destroy Wiping will usually work if your plan is to resell your old device, but if you really want to make sure that the information is gone for good, and you are going to throw the device away anyway, make sure to destroy it. Many consumers and businesses elect to use a professional document shredding service. I talked to Harold Paicopolos at Highland Shredding , a Boston Area, (North shore, Woburn Ma) on demand, on-site and drop off shredding service. Harold said “Theft, vandalism, and industrial espionage are ever increasing security problems. Today’s information explosion can be devastating to your business. Most consumers and businesses may not know that they have a legal responsibility to ensure that confidential information is not disseminated.” The reality is, if security is important to you or your company, then shredding should be as well. The goal, of course, is to make it impossible for thieves to access the data you have and/or discard. Recycle If you want to recycle your device, make sure that you only use a company that is certified and does downstream recycling. Know that recycling offers NO security for your information. They should be part of the R2, or Responsible Recycling program or the e-Stewards certification program. Otherwise, your data could end up in the wrong hands. Also, if you recycle or donate your device, make sure to keep your receipt. You can use it when you file your taxes for a little bit of a return. Robert Siciliano is a Security and Identity Theft Expert. He is the founder of Safr.me a cybersecurity speaking and consulting firm based in Massachussets. See him discussing internet and wireless security on Good Morning America .