As we already figured out, a blockchain consists of blocks of data. These blocks are stored on small servers aka nodes. This small server can be any kind of device — from cell phone in some blockchains to the monstrous computer. Nodes build the entire infrastructure of a blockchain. They store and spread the blockchain data. A node is a device that contains a full transaction history of the used blockchain.
So, Why do we need nodes?
When a miner adds a new block to the blockchain, it sends the block to all the nodes on the network. Based on the block’s validity of the signature, nodes accept or reject the block. When a node accepts a new block of transactions, it saves and puts it on top of the rest of the other stored blocks.
Here are the main nodes functions:
– Nodes store blockchain transaction history.
– Nodes check if a block is valid.
– Nodes broadcast this transaction history to other nodes that may require to synchronize with the blockchain.
The entire blockchain can run on a single node, but if it would be stored on a single device, it would be very weak to stuff like power interruption, crashes or hackers. When the blockchain data is spread over many devices, it will be very difficult to somehow affect blockchain data. Even if all nodes go offline, it only needs one node with the full blockchain history to come back online and get access to all data.
Who can launch a node?
Anyone can launch a node by downloading the transaction history of a blockchain. Most of the blockchain enthusiasts are running nodes voluntarily. They do this in order to support the community, the developers, and to feel themselves part of something big. The size of the node can be different depending on the blockchain — from several megabytes to hundreds of gigabytes.
What about the masternodes?
Some blockchains also carry the so-called masternodes. In addition to the duties of a node, masternodes also support other functions on the blockchain, such as administering voting events, implementing execution of protocol operations and many other functions. Masternodes are usually online 24/7 and require much more memory than normal nodes. Running a masternode requires much more resources like electricity and storage space.
Who can run a masternode?
Unfortunately, running a masternode is not available for everyone. It requires the host to deposit a quite large amount of crypto. This deposit is taken pledge when the masternode host violates the blockchain rules. The more deposit is made, the higher reward the host will receive for running the masternode.