Let's understand what a node is in blockchain. Essentially, it is a computer or server that stores information about all transactions and constantly communicates with other nodes in the network. It is thanks to these nodes that blockchain remains decentralized — data is not concentrated in one place but distributed across thousands of computers worldwide.

I often encounter the question: why are nodes needed at all? The simple answer is — without them, blockchain simply cannot exist. The network of nodes is synchronized with each other and constantly exchanges information. This allows maintaining transaction speed while preserving the main advantage of cryptocurrencies — decentralization. Even if internet access is blocked in one country, the network will continue to operate because nodes are spread across different regions.

Now about types of nodes. Let's start with full nodes — the foundation of any blockchain. Such a node stores absolutely all information about the network from its launch. When you send coins, all full nodes see this operation and save it. In Bitcoin, tens of thousands of full nodes operate simultaneously. The downside is — if you set up such a node for the first time, you need to download the entire blockchain. For Bitcoin, it was 438 gigabytes back in 2022, and now it’s even larger. Synchronization can take several weeks.

If your computer's power is insufficient, you can use a lightweight node. This is a more streamlined option — such a node does not store the entire history, only information about the block it is connected to. Lightweight nodes connect to full nodes and receive the necessary data from them. The main advantage is — they work even on mobile phones, and synchronization takes seconds.

There is also an intermediate option — pruned full nodes. They download the entire blockchain once and then automatically delete old data when a set amount of memory is reached. For example, you can configure a node for 10 gigabytes.

Now about specialized nodes. Mining nodes are used in blockchains with a Proof of Work algorithm — they solve complex mathematical problems and find new blocks. This requires powerful equipment — processors, graphics cards, or specialized ASIC devices. In blockchains with Proof of Stake, instead of mining nodes, staking nodes operate. Here, rewards are earned not for calculations but for holding a certain amount of coins in the account. This is much cheaper — no need to buy expensive hardware.

Master nodes are an enhanced version of full nodes with additional functions. They help ensure anonymity by mixing transactions between different wallets. To run a master node, you need to meet the blockchain’s conditions — usually, this means holding a certain amount of coins in your account. The system rewards this by distributing a portion of the miners’ fees.

There are also Lightning nodes — second-layer nodes for Bitcoin. They only verify transactions that concern them, so they work incredibly fast. This solution is for microtransactions.

In each network, there are also validators — nodes that verify and approve transactions. And oracles — they transmit information from external systems into the blockchain, such as current currency exchange rates for decentralized services.

One important detail about how nodes are updated. When developers want to make changes to the protocol, this is called a fork. Soft fork refers to soft updates that do not break compatibility. If only some nodes accept them, the network will still continue to operate. Hard fork involves significant changes. If the community splits over opinions, the network may divide into two separate blockchains. Remember how Ethereum in September 2022 transitioned from Proof of Work to Proof of Stake — then mining nodes disappeared, and staking nodes with validator functions appeared.

Users who run nodes receive rewards for providing the network’s computational power. This motivates people to participate in decentralization. So if you want to truly understand how blockchain works, try running your own node — it will open your eyes to many processes.