A blockchain – is a continuously growing list of records, called blocks, which are linked and secured using cryptography hash. Each block typically contains a hash pointer as a link to a previous block and a timestamp. By design, blockchains are inherently resistant to modification of the data. For getting hash used SHA-256
pip install Flask
git clone https://github.com/colyk/flask-blockchain.git
cd flask-blockchain
python server.py
Now head over to http://127.0.0.1:5000/, and you should see main page of blockchain, where you can add new block, check blocks integrity and mined blocks using POW algorithm.
POW ( proof of work) is a piece of data which is difficult (costly, time-consuming) to produce but easy for others to verify and which satisfies certain requirements. Producing a proof of work can be a random process with low probability so that a lot of trial and error is required on average before a valid proof of work is generated. Bitcoin uses the Hashcash proof of work system.