Blockchain Other Uses#Along with bitcoin transactions, the blockchain can be used to store any digital data. While some view such uses as “bloating the blockchain”, bitcoin’s decentralized nature means that they cannot effectively be stopped. This led the developers of Bitcoin Core, the official bitcoin client, to introduce an official mechanism for adding arbitrary metadata to transactions in early 2014
Other Blockchains#Bitcoin mining network performs quadrillions of calculations every second that maintain the integrity of its blockchain. Other blockchains are not remotely as secure, but they innovate much faster. Sidechains, an innovation proposed and developed by the startup Blockstream, allow for the best of both worlds; the creation of new blockchains "pegged" to Bitcoin, so that value can be transferred between them, which can conceivably be automatically secured by Bitcoin miners via “merged mining.”
The sidechains vision of the future is of a vast globe-spanning decentralized network of many blockchains, an intertwined cable rather than a single strand, each with its own protocol, rules, and features — but all of them backed by Bitcoin, and protected by the Bitcoin mining network, as the US dollar was once backed by gold. Sidechains can also be used to prototype changes to the fundamental Bitcoin blockchain. One catch, though: this will require a small tweak to the existing Bitcoin protocol.