I recently purchased an Apple Xserve from eBay that I plan on using it as a web server. The server was previously owned by a large branding company, with offices in New York and California. How do I know this? They were not the ones selling this computer on eBay. So how could I know? Well, whoever took this server out of service, never properly erased it's hard drives! The hard drives were loaded with hundreds of gigabytes of private, personal information.
What's worse, this server went out of service in 2012. But it is 2018. Where has all this data been for the past 6 years? Who knows. Hundreds of current employees, past employees, and independent contractors who worked with this company have potentially had every last bit of their personal info leaked all over the internet.
This was a major failure by this branding company's IT department and a major security breach -- unless the data or computer were somehow stolen. Then it was just a security breach and not an IT failure.
There is a moral to this story that every last technology user CAN and absolutely SHOULD learn from. Even though there's nothing any non-IT employee at this company could have done to prevent this, this can happen just as easily to every old computer, hard drive, or phone that you throw away, recycle, sell or give away.
Everything MUST be securely erased! You need to securely erase your data yourself, or make sure you give it to someone you trust to erase it. (MacFixer securely erases all hard drives that customers give us for recycling, inside or outside of a computer, whether the drive is failing or fully functional)
Simply deleting important files is not enough. It is extremely easy for someone with the right software to scan all empty space on a hard drive and recover tons of deleted files. This software is inexpensive and completely legal, as there are many legitimate reasons you would want to scan your own drives this way. Few people have enough expertise to know where every program they use, stores every last bit of it's data, and your data. There will always be some pieces left behind.
You can physically destroy your drives, smashing them with a hammer, for example. But you might not know how to remove the hard drive safely from an old computer, and you may not want to smash an old computer, either. I prefer doing a secure reformatting that writes over the entire drive 2 or more times. That makes the drive truly, completely, securely erased.
Don't just throw your device in the trash, thinking "what important info do I have? You want to see my vacation pics?" Well, yes they will look through all of your pics. They will also look through all of your passwords you have stored on the machine, every time you've said "remember my password". You only need the computer's login password to unlock that. How secure is your login password? They can also view your browser history. They can look at all of your documents. Do you do your own taxes? Your tax return is an absolute jackpot for an identity theif. There were full tax returns of people that worked at the "branding" company on the server I purchased. I can't overemphasize how serious this is. Everybody has sensitive information on their computer. And lots of non-sensitive, but still personal information. Criminals with just a little bit of IT knowledge will not hesitate to grab hard drives and computers right from peoples trash to see what they can find on them.
If your head is spinning and you don't know what to do, here it is in a nutshell:
Always securely erase all of the data off of your devices before you dispose of them, NO MATTER HOW you are disposing of them. Every kind of device will have a different way of doing this, so you must learn the right way for your device -OR- be sure you are disposing of them by giving them to someone you FULLY trust to securely wipe the data off (like MacFixer).
The harder part can be determining which devices have personal data on them. All computers, tablets and phones do. Some set-top boxes and tv's might have some basic info. And many copy machines save a copy of every single document you ever copy, to an internal hard drive.