Bitcoin

Bitcoin is the first cryptocurrency on a blockchain. The concept was published October 2008 in a whitepaper by Satoshi Nakamoto on the Cyberpunk mailing list.

It is using a Proof of Work consensus algorithm and is until now (2021) by far the largest cryptocurrency in market capitalization.

Miners on the Bitcoin blockchain receive a reward (some bitcoins) for creating a new block first.

The reward is halved every 210,000 blocks. That is about once every 4 years

The total amount of bitcoin that can be mined is limited to about 21 million (20,999,999.9769 exactly). After that validators can only be rewarded by transaction fees. This amount will be reached in 2140.

Chalenges

• The vast amount of energy use in mining.
• Speed and scalability. As the Bitcoin blocksize is only 1MB and there is only 1 block generated per 10 minutes the volumes of transactions that can be processed is very limited (about 7/sec). The proposal to fix this (partly) by increasing the blocksize caused the hard fork of the BitcoinCash blockchain. The lightning network, where numerous transactions can been done between parties before the result goes to the blockchain is a solution that is adopted by Bitcoin.