What is Blockchain? Well, a good starting point is Blockchain (database) - Wikipedia but also the following:
- Decentralised Database or Distributed Database, where data is stored in multiple places. Each entry is chained to the previous
- Process Automation, you can create atomic contracts with defined workflow/logic, built into the database
- Cryptographic Security, standard PKI, bringing integrity
- Value Transfer, moving between participants in the network, securely transfer ownership of asset
- Immutable, you can't change it, although some are working on a changeable version
Where is this technology useful? Cryptocurrencies, ecosystems, broken markets (like buying and selling houses in the UK).
Mark Russinovich did a presentation on Blockchain Blockchain Overview.pptx - Microsoft PowerPoint Online which is worth reading.
- Bitcoin and Blockchain are not
- Each Blockchain has a single "genesis" block
- There is a single "chain"
- Each Block references a previous block
- Blocks can have multiple transactions within them
- Each Block is a list of transaction
- Bitcoin does fork but they come back, where longest chain wins, orphan blocks or on the shorter chain
- code should be open, especially for open chains
- Hyperledger provides permissions
See the following:
Bitcoin Block Explorer - Blockchain
Blockchain 101 - A Visual Demo - YouTube