What is a Node in a Blockchain Network?
Hi! I am Kendra, lets look into what a node in a blockchain is.
Let’s begin by explaining what a blockchain node is. In general, every participant in a coin’s network is a node. There are different types, but each of them shares one specific characteristic – you’ll require specific hardware in order to host or simply connect to one.
Blockchain technology is decentralized by nature – one of the key properties that made it so appealing to the wide public. It’s based on the principles of a P2P network. In most networks, there are no dedicated servers, not one authority, but a consensus among users. As they’re all crucial to the security and integrity of the network, becoming a member of a certain crypto coin community is not only exciting but also a responsibility.
Take Bitcoin for example – you have two types of nodes. Full nodes which store a copy blockchain and thus guarantee the security and correctness of the data on the blockchain by validating data. The second type is a lightweight node – each user participating, who needs to connect to a full node in order to synchronize to the current state of the network and be able to participate.
The Consensus in a Decentralized Network:
In the previous section, I mentioned consensus. You might be wondering what that relates to in crypto terms. The rules by which a blockchain network operates and confirms the validity of information written in blocks and/or work performed is termed “consensus”.
As we’ve already covered, crypto currencies operate on a decentralized P2P network. As you can imagine, agreeing on something with a large number of people is bound to lead to complications. This is where consensus algorithms come into play. The most common ones are Proof of Work and Proof of Stake.
No matter which one has been chosen for a coin, they both have a crucial factor in common – reliance on full nodes for enforcing of rules and validation of transactions. While consensus must be achieved by a certain type of nodes, the beauty of a P2P network is that anyone can become a full node and thus achieve higher levels of independence and decentralization.
I’ve previously given an example using Bitcoin – users are free to download the whole blockchain and validate blocks, thus increasing security, as more and more copies of the ledger are created and used for reference. The prime crypto currency offers one of the highest levels of decentralization, compared to EOS for example, where becoming a validator needs to be voted by a set number of users and the available positions are limited. This opens the network to corruption and manipulation.
The most common threat to a blockchain is the 51% attack, where more than half the network “power” is concentrated in one entity (be that a single person or collaboration between users). That allows said entity to change consensus rules as it sees fit, which could lead to a monopoly where everyone is either forced to continue with the new rules, hard fork or abandon a project. While strict enforcement is a given during the day to day operation of the blockchain, for evolving the network, alterations need be voted on by the community and thus achieve long-term success.
In short, a hard fork is a change to the network consensus algorithm. Every alteration that is not compatible with the previous version of the client used, is considered a hard fork.
Another way of introducing changes to a network is via a soft fork. Contrary to hard forks, with this type of alteration, there’s no mandatory rule for users to update their nodes.
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