But how does bitcoin actually work? (2017)

The math behind cryptocurrencies.
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An equally valuable form of support is to simply share some of the videos.
Special thanks to these supporters: http://3b1b.co/btc-thanks
This video was also funded with help from Protocol Labs: https://protocol.ai/join/

Some people have asked if this channel accepts contributions in cryptocurrency form. As a matter of fact, it does:
ENS: 3b1b.eth

2^256 video: https://youtu.be/S9JGmA5_unY

Music by Vincent Rubinetti: https://soundcloud.com/vincerubinetti…

Here are a few other resources I’d recommend:

Original Bitcoin paper: https://bitcoin.org/bitcoin.pdf

Block explorer: https://blockexplorer.com/

Blog post by Michael Nielsen: http://3b1b.co/crypto
(This is particularly good for understanding the details of what transactions look like, which is something this video did not cover)

Video by CuriousInventor: https://youtu.be/Lx9zgZCMqXE

Video by Anders Brownworth: https://youtu.be/_160oMzblY8

Ethereum white paper: https://goo.gl/XXZddT


Other Videos by video creator



this was awesome! I was having trouble on understanding the nodes vs. miners as well as the random number / difficulty adjustment but this totally cleared it up!
It’s an extremely information dense lecture. You have to watch portions of it again and again to grasp the underlying concepts. But once you’ve finished it, you feel so damn confident.
5 years later and I still comeback to this Blockchain explanation to check if my understanding, love it
You have no idea how much I’ve tried to find an article or video actually explaining how cryptocurrencies work. Everyone else just goes around with analogies. They probably don’t understand fully themselves. Thanks man.


This is the clearest video I’ve ever seen, and I still don’t get it.
10:00 “The history of transactions is the currency” interesting Edit: 17:30 I love how I now know what a block chain is, and it wasn’t as mind blowing as people on the internet made it seem. And I’m pretty sure blockchains are done in introductory coding courses. (Though not as complex). Edit 2: 18:25 so THAT’S why mining is profitable. I get it now. That circles back to the claim made ~10 mins in. Edit 3: 21:15 So, bitcoin ‘authority’, in essence, is computing power, and bitcoin ‘identity’ is the a blockchain made by the original owner? Great video. As you can see I am still shaky on complete understanding, BUT this was the only useful explaination of Bitcoin and crypto I’ve seen so far (for me). So I am greatful. and maybe this will lead me to understanding others.
Prior to watching this I didn’t really understand the link between mining and validating the transactions. Its quite interesting how the system can self-adjust to make sure that mining\validating is always profitable, and therefore even if there is a big crash in mining profitability it should just result in a slowdown of transactions until the system balances. I guess the issue is that there is a big problem if the coin is used for real large scale commerce\business that rely on guaranteed volume. If a large enough proportion of bitcoin transactions were for real vital goods and services, then a crash in mining profitability could drive he value to zero since the value would be much more tied to the amount of volume the system can handle. Lack of trust could continually inflate it, which would then continually make it harder to restore validation capacity. Volatility is an issue for real world business even if the overall trend is continually upwards. If I am correct, then it would suggest that bitcoin will remain a speculation asset and a store of value rather than a replacement for sovereign currencies?
at around 20:30, theyre discussing how it isnt viable for Alice to try to commit fraud because she cant out-compute the other miners on the network all by herself. could someone explain what would happen if a group of miners (that formed the majority of the network) decide to commit fraud together?
>>  It’s 100% possible. And in fact, the top 4 miners of bitcoin have more than 50% of the network’s total hashing power. However, if you have 50% of the total mining network’s computation, you’re probably better off using it to make ~$2.2 Million a day with honest mining than you to defraud a single individual.


>> the specific name for this scenario is a “50% attack”