Namecoin is a blockchain-based DNS that allows users to register domain names with a ".bit" domain. Namecoin was the first fork of the Bitcoin protocol and it aims to remove centralized control over domain registration. It was the first cryptocurrency to use Auxiliary Proof of Work (AuxPoW) as a consensus mechanism,
where a child blockchain is dependent on the Proof-of-Work consensus of the parent blockchain. This allows for Namecoin and Bitcoin to be mined simultaneously, and when a new block is created on Bitcoin, it will also be added to the Namecoin blockchain.
Namecoin is a very important project that represents one of the best use cases of blockchain technology in protecting free speech and resisting censorship on the internet. It is powered by the NMC coin. The decentralized DNS provides more security from hackers and government intervention.

XinFin is a blockchain technology company that has developed the XDC protocol. XinFin's hybrid blockchain enables peer-to-peer contracts on a regulated payment infrastructure. Their goal is to create an open source marketplace platform that will reduce inequalities in global finance.
The XDC blockchain is built upon Quorum, a permissioned blockchain developed by J.P. Morgan. Quorum was developed as a layer upon the Go implementation of the
Ethereum protocol. XDC's consensus mechanism allows for new blocks be created in a two-step process. In the first step, the transactions to be included in the new block are voted upon by all participating nodes. In the second step, one node is selected as the leader or block maker randomly. The block maker node then creates the new block.
XInFin is powered by the XDCE token.

Blockstream is a private, for profit, blockchain technology company, that has played a key role in helping to develop, and fund, many of the key features of the Bitcoin Core platform. Blockstream is focused on developing bitcoin applications and has raised significant funding from several large investment funds. The company also employs several developers that are very influential within the Bitcoin Core development project. This, as well as being of Bitcoin's largest donors, has led to some criticism about conflicts of interest.
Blockstream is developing a number of Bitcoin applications that are intended to encourage adoption and improve transaction times on the bitcoin network. Their primary focus is on Sidechains, which are are extensions to existing blockchains that improve their functionality. The company is also working closely with industry leaders to create the Bitcoin Lightning system that will support higher trading volume and faster transactions on the bitcoin network. Blockstream is also developing a data feed, satellite network, and other applications that they hope will make blockchain more accessible.