A node has a different meaning based on its context.
In the world of networks, telecommunications networks or even computers, nodes have well-defined characteristics: they can be a redistribution point or a communication endpoint. We can say more generally that a node is a physical network device. In order not to miss anything, however, there are also some specific cases in which it is necessary to use virtual nodes.
Cazoo, talk about drinking!
It goes bon. A network node is a point where a message can be created, received or transmitted. As already mentioned, there are different types of Bitcoin Nodes: full nodes, super nodes, miner nodes and SPV clients.
Where the Blockchain is designed as a system distributed, a network of nodes allows Bitcoin to be used as a decentralized peer-to-peer (P2P) digital currency, incensurable and decentralized, that is, without necessarily having to exist intermediaries to validate trades, exchanges, transactions between users.
I blockchain nodes they must therefore act as a communication point and must be able to have some properties, so that they can perform some functions. Any device that connects to the Bitcoin interface, such as a computer, can be considered a knot, since all nodes are connected within the blockchain. What can these knots do? They communicate. They transmit information about transactions and blocks of its distributed computer network with Bitcoin's peer-to-peer protocol. Eye: there are different types of Bitcoin nodes.
Full nodes are those nodes that concretely give Bitcoin security and support its structure: they are essential for the functioning of the entire network. Maybe you've already read them somewhere and seen them called full validating nodes: they call them that because participate in the process of verifying transactions and locks according to the rules that were imposed by consent of the system. Full nodes can transmit new transactions and new blocks to the blockchain.
Normally a full node must download a copy of the entire blockchain, with all its blocks and transactions (even if it is not a necessary requirement to be considered a full node - even a single part of the blockchain can be downloaded). A Bitcoin full node can be set up following many different software implementations, where the best known of all is called Bitcoin Core(here the link for his github). It is not for everyone! Here are the minimum, but minimum, minimum requirements to be a Bitcoin Core full node:
Desktop or laptop with a recent version of Windows, Mac OS X, or Linux.
200GB of free disk space.
2GB of memory (RAM).
High speed internet connection with uploads of at least 50 kB / s.
Unlimited connection or with high upload limits. Or make sure that in your tariff plan, if you make a hotspot, 200 giga per month in upload and 20 in downlaod are included.
The full node must be able to work for at least a quarter of the day (6 hours) but it is very appreciated that it always remains active, 24 hours a day.
Thousands of different volunteers and even organizations are working hard to be full nodes and thus be able to help the Bitcoin ecosystem. As of today (May 2021) we count 9615 active public nodes in the Bitcoin network. And we're just talking about public nodes, that is, the visible and accessible Bitcoin nodes - which are also called listening nodes.
Yes Sherlock, there are also non-listening nodes, hidden and invisible knots. These hide behind a firewall to operate, using privacy protocols such as Tor, or, even simpler and more secure, they are not configured to receive connections.
Listening Nodes (Super Nodes)
Un listening node o super node is a publicly visible full node: it communicates with other nodes that want to talk to it and exchanges information. So used the super node is both a communication bridge and a source of data: a super node is a redistribution point.
If you want to be a reliable super node, you must always be active, 24 hours a day, so as to be able to transmit a flood of connections: the history of the blockchain must be documented, all transactions must be recorded with their data on all nodes throughout the world. It goes without saying that it is even for fewer people: the required computing power, as well as a better internet connection, are needed.
The time of mining has passed. Don't start undermining. Today, in order to participate competitively in the Bitcoin mining process, it is essential to invest in specialized programs and hardware, which run in parallel with the Bitcoin Core to try to mine blocks. A miner, or a person who uses these powerful computers, can decide to work alone (only miner) or in groups (pool miner).
While the lone wolves, the only miners who asked their grandmother to be able to use the cellar for a while to do stuff with computers, while they make use of their locally downloaded copy of the blockchain, those who mine in pools, in swimming pools of miners, well they work just together, and each contributing their own resources (hash power). In a mining pool it is the sole responsibility of the pool administrator to maintain a full node: he is a full node pool miner.
Lightweight or SPV client
Also known as Simplified Payment Verification (SPV) clients, clients lightweight they use the Bitcoin network but do not act as a full node. SPV clients therefore do not contribute to network security: they are not required to have a copy of the blockchain, and they are never asked in the transaction verification and validation process.
The SPV client has a fundamental function: it allows any user to check whether or not some transactions have been included in a block, without having to download all the data of the block. How do they do it? They request some information from other full nodes (super nodes). Lightweight clients act as communication endpoint and are used by different wallets (wallets) to store cryptocurrencies.
Client vs Mining Nodes
Importantly, maintaining a full node is very different from maintaining a full mining node. While miners must invest money and resources to purchase and use highly expensive hardware and software (remember how much people complain about the electricity used to mine bitcoins), anyone can maintain a full validating node. Indeed, without the full validating node, the miner cannot do anything: before trying to mine a block, a miner must receive the ok from a full node, which certifies and validates the pending transactions. So then the miner can create a block that has applied to host that information (with a group of transactions) and tries to mine the block. Here the blockchain is about to be updated again: if the miner manages to find a valid solution for the block it can now be transmitted to the rest of the blockchain and the full nodes verify its validity. Ultimately, the consent rules are determined and guaranteed by the distributed network of validating nodes, not from miners.
The Bitcoin nodes are in communication with each other through the P2P Bitcoin network protocol and by constantly communicating with each other, they guarantee the integrity of the system. What if there is a knot that doesn't behave well, that acts dishonestly, that is mischievous, that tries to propagate wrong information? In blockchains, information flows: that node is quickly recognized by honest nodes and is promptly disconnected from the network.
How much can I earn by maintaining a full validating node ?? '?
A cazoo! No economic rewards are offered: it is determined by the trust of the users, it provides peace of mind, security, privacy to the users. Full nodes are real game referees: they certify that the rules are followed. They protect the blockchain from attacks and fraud (such as the double-spending) and they don't have to trust anyone else.