How Blockchain Nodes Secure a Decentralized Network

The breakthrough innovation of blockchain technology is its ability to function as a decentralized entity without any central authority. Instead, a decentralized network is secured by many distributed nodes. Here we’ll explore how nodes work to secure blockchain networks, various types of nodes that exist in the decentralized space, and blockchain mining. Although there have emerged many different types of consensus mechanisms – proof-of-stake, for example – we will limit ourselves to proof-of-work-secured blockchains for the sake of this article. 

How Nodes Work 

Nodes on a blockchain, simply put, are links in the chain of consensus. When a person or entity becomes a node, they download a full (or partial) record of the entire blockchain with all transactions on every block in history. Since a copy of the record is distributed around the world to various computers and devices, the possibility for a malicious individual to defraud the blockchain is nearly zero – they would need to track down and change every single copy of the record on every single node, a quite impossible feat which would take more resources then it’s worth.  The distributed nodes also serve to protect the system against double-spending and fraud, since all of the transactions must add up on every node.  In summary, nodes on a blockchain secure the network, without them, the blockchain ceases to exist as a secure and reputable record. 

Different Types of Nodes

Not all nodes are created equal in a PoW network. This inequality comes from the fact that blockchains contain immense amounts of data that must be stored by the node’s computer/device, and not every entity that wishes to become a node has this kind of storage real estate. Light nodes download individual blocks one at a time. Pruned full nodes download the entire blockchain and then ‘prune’ away the blockchain’s history until the desired storage amount. Although these storage-friendly node types are important for democratizing access to blockchain mining and consensus, they cannot exist independently of archival full nodes which have downloaded a full copy of the blockchain in its entirety. Archival full nodes are indeed the network’s backbone, and absolutely essential for mining new blocks.

Blockchain Mining

Not only do blockchain nodes secure the network; they are also responsible for mining new blocks on the chain. Any node can mine blocks as long as they have the computation abilities to solve hash functions and verify the truth of the transactions on a new block.

Environmental Concerns

Although proof-of-work is the most secure and most fully decentralized way to secure a blockchain network, the amount of energy consumed in the mining process amounts to the energy consumption of entire countries! To address this problem, other forms of blockchain consensus have emerged. Proof-of-stake, for example, relies on staking by validators. Proof-of-authority makes use of a limited number of authority nodes to validate blocks.   
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