In 2008, Bitcoin was launched as a peer-to-peer database that relied on a new data structure
referred to as the ‘blockchain’. The blockchain consists of blocks, where each block holds a set of transactions and a reference to the previous block. This helped create a chain of all transactions that ever occurred. This data structure is replicated across all participating nodes so that every participant is aware of the transactions without having to get them from a central authority.

Look at this great animated introduction from GoldmanSachs

In other words, the blockchain is a decentralized ledger, or list, of all transactions across a peer-to-peer network. The invention of the blockchain is fairly recent and related to Bitcoin, as presented below.

The history of consensus algorithm and the well know Byzantine fault tolerance problem is older (from KPMG report written by Sigrid Seibold, click to enlarge).

Blockchain Platforms and Ecosystems

We can split the ecosystem in two: separating permissioned from permissionless blockchain platforms. Most platforms are only implementing one consensus protocol, which impacts directly the number of nodes supported in the performance offered (from KPMG report written by Sigrid Seibold, click to enlarge).

Some interesting permissionned blockchains (aka. private blockchains):

An example of usage of private blockchains:

Then, a list of permissionless blockchains projects:

Metaprotocol based platforms working on top of permissionless blockchains and adding new features:

Some providers are willing to offer Blockchain As A Service like: ArdorIBM BluemixMicrosoft AzureStratis. You can also have a look at the Ethereum Network or at Bitcoin Network.

Interesting Applications

Blockchain for IT

  • BigChainDB: Blockchain Database.
  • BlockCypher is the infrastructure fabric (API) for blockchain applications.
  • DNSChain a blockchain-based DNS and HTTP secure server
  • FileCoin: Data storage network and electronic currency based on Bitcoin.
  • Golem: Golem network is going to create the first decentralized global market for computing power of users’ machines combined with flexible tools for developers to distribute and monetize their software.
  • Interledger: It connects two networks, even if those networks speak a different language. 
  • iPDB: A planetary-scale blockchain database for the world.
  • iPFS: A peer-to-peer hypermedia protocol to make the web faster, safer, and more open.
  • Infuria fault tolerant and scalable Ethereum and IPFS nodes.
  • IPLD (Interplanetary Linked Data): Allows data blobs to flow through the walls of one network to another. 
  • SAFE for advanced peer-to-peer technology that joins together the spare computing capacity of all SAFE users, creating a global network.
  • Storj: End to end encrypted distributed object storage.
  • Solidity programming language and Truffle Ethereum swiss army knife

Interesting English Resources

English Books 

Conference « Le Big Bang Blockchain ». Les enjeux de mobilité et la blockchain- ESCP Europe, 14 janvier 2016.

Conference : « La puissance algorithmique au service de la révolution des services : les nouvelles opportunités offertes par la technologie Blockchain". Chambre de Commerce et d’Industrie de Paris Ile-de-France, le 11 Mai 2016.