Bitcoin is the first digital currency based on blockchain. It solved the double-spending problem and enabled peer-to-peer transactions on a large scale. Bitcoin was designed to work as a trustless digital currency that would function without government oversight or a central bank.
Bitcoin was developed by Satoshi Nakamoto, whose identity has never been confirmed and has become the subject of great intrigue. Bitcoin builds upon on other cryptographic and digital currency projects that came before it, but its use of blockchain made it more viable. Nakamoto originally released his white paper and open-source software on a cryptography forum. He mined the first block of the Bitcoin chain, called the genesis block in January 2009.
Bitcoins are created as a reward for a process known as mining. One of the core innovations of Bitcoin, is its consensus algorithm, which creates an incentive system that rewards miners for confirming transactions.
Hal Finney, who developed the first reusable proof-of-work system (RPOW), several years before, was the first Bitcoin adopter and received the first bitcoin transaction ever recorded on its blockchain.

Stellar is a decentralized protocol for sending and receiving money, in any pair of currencies, directly on the internet. Stellar enables users to transfer money on their network directly, without banks, and without fees. It was originally created by Jed McCaleb, the founder of Mt. Gox and co-founder of Ripple.
Stellar has its own native coin called Lumens (XLM). All users must hold a minimum of 20 Lumens in order to ensure their authenticity and to maintain a wider distribution and free flow. Users must spend 0.00001 XLM in order to transfer fiat currencies. This provides the network with more liquidity for less popular currency pairs. Lumens are an inflationary currency with a fixed increase rate of 1% per year.
The network uses the Stellar Lumens Consensus Protocol (SCP). Unlike PoW or PoS consensus mechanisms, SCP relies on a Federated Byzantine Agreement (FBA), in which specific groups of nodes are chosen to arrive at transaction agreement. This provides the Stellar network with more decentralized control.
Lightyear.io, a for-profit entity of Stellar, was launched in 2017 as the commercial arm of the company.

PascalCoin is the first blockchain that can be deleted, and reduces the dependency of the entire blockchain history to verify transactions. It is a Proof-of-Work (PoW) cryptocurrency that places a strong emphasis on achieving the same level of scalability as credit card networks such as VISA. Pascal's architecture is based on an innovative cryptographic structure called the SafeBox. It facilitates faster transactions by storing account balances separately from the blockchain. The SafeBox only uses the last 100 blocks on the chain to update transaction history. This allows the network nodes to synchronize much faster while preserving the security of the blockchain, and reducing the computing resources needed to maintain it.
PascalCoin also enables simplified account naming to make it easier to transfer funds.