This guy lost 8,999 of his 9,000 bitcoins because he didn't know what a "change address" is

And he was just testing his backup wallet to make sure he won't lose them.. the irony :|original post: http://bit.ly/2q31srO post is from 2010 when bitcoin wasn't worth that much, but still...The reason he lost them was that back then you had to backup your wallet with every new address that was added to it. When you send a bitcoin transaction (as explained in the original post) the "from" address is spent completely, sending to at least 2 addresses: 1st address is the recipient of the bitcoins you intend to spend, and the 2nd address is the "change address" where all the leftover bitcoins are sent to. The change address is created as part of your personal wallet.Luckily, today we have modern deterministic wallets (HD wallets) that contain a seed. That seed is used to generate unlimited new addresses, including the change addresses, so today you don't have to re-backup your wallet after each transaction. One is enough.Moral of the story: Make sure you only use an HD wallet, in case you haven't updated your wallet software in years. via /r/Bitcoin http://bit.ly/2EkbFTG