What happens to my two Bitcoins (just for example) if I lose my security key? I do not have any Bitcoin at the moment. But, I am quickly learning about Bitcoin as I want to very soon make my very first purchase of some amount of it. My question has to do with there being a finite amount of Bitcoin in circulation. Today about 17,000,000 (17 million) Bitcoins are in existence. By year 2140 as I understand it there will be no more than 21,000,000 (21 million) Bitcoins in existence. Furthermore, my understanding is that I am the only person with access to my Bitcoin through my private security key. Now, my question is. If I lose my security key to, let's say, one of my Bitcoin wallets that has maybe 2 Bitcoin in it. Then, what happens to that 2 Bitcoin in the context of the 17 million Bitcoin currently in existence. Who can find and use those 2 Bitcoin that I "lost". Or, do those 2 Bitcoin get lost forever, because I'm presuming no one ever will find/guess my lost security key? An analogy is, if I lose a hundred dollar bill, someone will likely find it and be able to use it to put it back into market circulation. However, if the hundred dollar bill gets flushed down a sewer drain, then it gets permanently removed from market circulation. So, I'm wondering, do the 2 Bitcoins in my example that I "lost", do they permanently get removed from market circulation. And, if so, then does that mean that in 2140 there will be 2 Bitcoins fewer in the total market circulating, for example, 21,000,000-2 would make it 20,999,998 Bitcoins in circulation. Or, can those 2 lost Bitcoins be *replaced* by Bitcoin mining over time so that the market has the full 21 million in circulation.