A node in blockchain is defined as a participant in the network, thereby ensuring the security and decentralization of the blockchain network. In general, any computer system that is connected to the blockchain network is referred to as a node. Blockchain technology is actually formed from decentralized systems that do not have a central secret server or a single controlling entity, and the lack of such a central entity is compensated by the presence of nodes in the blockchain, and these nodes are what make it possible to carry out peer-to-peer transactions in the context of blockchain networks.
It is interesting to know that the more the number of nodes in the blockchain increases, the stronger the infrastructure of such a network becomes and, naturally, its scalability will also increase. It goes without saying that the concept of a node in blockchain also plays a key role in the consensus algorithm and has significant effects on it. In fact, when a node in the blockchain sends a confirmation, it is called a consensus algorithm, and the process of receiving such confirmations from nodes will be in two forms: the proof-of-stake algorithm and the proof-of-work algorithm.
To better understand the concept of a node in the blockchain, let's give an example; Imagine that you are going to play football with your friends, will such a possibility be possible without a field for football games?! If there is no suitable field for football, how will you enjoy your game?! In this example, the football players we are talking about are the same platforms, the football teams are the same blockchain networks, and the playing field is exactly the same concept as a node in the blockchain. In simpler terms, these are the nodes that allow blockchain networks to run on them. It goes without saying that these nodes, which form the infrastructure of the blockchain network, can be any type of device, laptop, computer, and even server.

Types of Nodes in Blockchain

Full Node

One of the main components of the blockchain network is the full node, so that if this type of node is not present in the blockchain, our blockchain network will practically fail. These nodes in the blockchain network have taken on the main task of confirming transactions, and the way a full node works is that it downloads a full version of the blockchain and acts like an independent server. It is interesting to know that if about 51% of the nodes are against making changes to the blockchain, the desired change will not be made and the blockchain must branch to make these changes, which is referred to as a hard fork; therefore, the main factor in creating hard forks in blockchain networks is the presence of these full nodes.
It goes without saying that this type of blockchain node itself is also divided into subsets, the main subsets of which are as follows:

Masternodes
A masternode is a type of full node that validates transactions and maintains a history of the blockchain but cannot add new blocks to the blockchain.
Authority nodes
An authority node is a node selected by an organization or community managing a blockchain. This node is found in blockchains where nodes must be verified.
For example, blockchains that use a proof-of-concept system only validate nodes that are run by node operators. These operators provide identifying information.
Staking Nodes
A staking node locks up cryptocurrency assets as collateral, a process known as staking. A blockchain that uses a proof-of-stake system selects staking nodes to validate blocks of transactions.
A staking node may consist of a single user or a staking pool, which is a large group of users who stake their cryptocurrency in a pool to have a better chance of being selected to validate blocks.
Miner Node
The main task of mining nodes is to validate floating transactions. In fact, this type of blockchain node does not need to receive all the information available in the network in order to mine the cryptocurrency of a new block, and is able to confirm the transaction and mine the new block solely by receiving the information of the previous block. These mining nodes extract new blocks in the network by using powerful hardware and allocating their system processing power for this purpose and receive rewards from the blockchain.
Of course, it goes without saying that people who intend to mine new blocks individually must activate the full node and use the full version of the blockchain network, but people who mine cryptocurrencies in groups do not need to do so and only the person responsible for the mining pool must do this.

SPV node and lightweight node
In general, instead of downloading a full version of the blockchain, a lightweight node checks which block is the last block in the chain at the current moment and is suitable for carrying out a transaction. This type of node is used in the daily process of cryptocurrencies and is based on and relies on full nodes. Light nodes exclusively receive a portion of the blockchain network and their main function is to prevent full nodes from failing and also to simply confirm transactions. It is interesting to note that given the limited functionality of this particular type of node compared to full nodes, Mel, their setup requires less equipment and cost. It goes without saying that this type of blockchain node does not have the right to participate in voting.
Super Node
Perhaps, compared to other types of nodes in the blockchain, it can be said that super nodes are a lesser-known class of blockchain networks. In general, super nodes are designed to perform some specialized tasks in blockchains. In other words, these super nodes are in a way the same full nodes that all members can see. In general, when a node in the blockchain wants to communicate with another node, the process of creating information and establishing such a connection is the responsibility of the super nodes, and in fact, they are referred to as the distribution point and communication path in the blockchain network. It is interesting to know that due to the 24-hour activity of this type of special node in the blockchain network, these nodes require higher power consumption and internet speed. The task of transmitting the history of the blockchain as well as the information of all other nodes in the world is the responsibility of super nodes.

The presence of nodes in the blockchain; the best solution to ensure network security
As you have seen in the above materials, the presence of nodes in the blockchain is very important and without them, the blockchain network faces fundamental disruptions. In fact, all blocks in the network are stored on these nodes and the consensus algorithm process takes place in the form of proof of stake or proof of work. In simpler terms, without nodes in the blockchain, the security of the network is shaken and the scalability of the network completely collapses. The more nodes in the network increase, the easier it is to achieve the goal of decentralization.