Light Node

A light node refers to a downloadable wallet connecting to full nodes for validating information stored on the blockchain. The reduced requirements of such nodes with regard to blockchain data ensure they run fast without stalling the underlying systems because of excessive data.

These nodes comprise partial information concerning blockchain histories and use less space compared to full nodes. They outsource the remaining information from the full nodes while the full nodes store the entire blockchain data and engage in the blocks’ validation and verification. Light nodes do not function independently. Instead, they depend on full nodes and often utilize them as intermediaries.

• A light node refers to a restricted form of a full node, containing only a partial list of the blockchain’s operations. Usually, it includes block headers rather than the entire transaction history.
• There are some key differences between light nodes and full nodes.  For example, the latter utilizes more storage and hardware compared to the former.
• A noteworthy disadvantage of light nodes is their data retrieval process. It is messy and slow.
• A key advantage of light clients is that they are cost-efficient.

A light node refers to software connecting to full nodes for interacting with the blockchain. Also known as a light client, it allows users to verify the incoming data instead of unquestioningly trusting that the data provider is honest and correct while utilizing only a small fraction of a full node’s computational resources. Note that light clients only utilize a small amount of storage, memory, and computing power to run on a smartphone as a browser’s part or embedded in any application.

Light nodes depend on full nodes for different operations, from asking for an account’s balance to requesting the most recent headers. The light client protocols’ design makes trust-minimized access to the blockchain as effortless as trusting any third-party provider.

To begin with, light clients must download the blockchain's block headers. They need not trust full nodes for all requests made. This is because block headers have a Merkle tree root, similar to a fingerprint of every piece of information concerning smart contract storage and account balances on the blockchain. Note that even a slight change in information can result in a change in the fingerprint.

Assuming that most miners are honest, the fingerprints contained by the block headers are assumed as valid. Knowing each block’s fingerprint, a light client has the ability to verify if the full node’s answer is identical to the fingerprint. This serves as a powerful tool that can prove that information is authentic without knowing about it beforehand.

Users can set up light clients by following the steps below:

1. Arrange for a laptop or computer that meets the desired blockchain’s specifications. As the name suggests, such nodes consume low data. Hence, one can often set it up on low-storage devices like mobile phones.
2. Download software or a program that enables one to access the ecosystem of the blockchain. For example, to run Ethereum light nodes, one can utilize a client called Geth. Note that running light nodes with Geth requires a storage capacity of around 400 MB, internet access, and acquaintance with command terminals.
3. After installing the program, the light node can be run. 

Let us look at a few light node examples to understand the concept better.

Example #1

Suppose a crypto user downloaded Geth to run a light node. He ran this command in the terminal window - geth --syncmode light. The light node interacted with the Ethereum network on a need-to-utilize basis with the block headers that consisted of summary information concerning the block’s contents. Any additional detail needed by the light client was received from a full node. The procedure enabled the node to interact with the blockchain efficiently while saving storage.

Example #2

In November 2022, a16z crypto, the crypto-focused unit of Andreessen Horowitz (a16z), a venture capital organization, announced that Horowitz will introduce an Ethereum light node named Helios. This Rust-driven light client will aim to provide the Ethereum network with trustless connectivity. The company claims the light client transforms into a provably local and secure remote procedure call (RPC) from an untrusted RPC. 

The advantages of light clients are as follows:

• They are associated with a low barrier to entry owing to minimal storage and bandwidth requirements. One can access them using a simple internet connection through a laptop, computer, or mobile.
• Running such a node is cost-effective.

Let us look at some disadvantages of light nodes.

• A light node wallet is associated with security concerns.
• These nodes do not have full functionality. They depend on full nodes for data.  Moreover, such nodes cannot be validators, which means they cannot take part in consensus.
• The data retrieval procedure is slow and messy. Moreover, it often fails. Hence, such nodes are not an ideal option if one has frequent data retrieval requirements.

People new to the cryptocurrency world often find it difficult to understand the concepts of light and full nodes and get confused. To fully understand their meaning and steer clear of confusion, one must learn about their critical differences. Let us find out what they are.

This article has been a guide to what is Light Node. Here, we compare it with the full node and explain its benefits, examples, limitations, and how to set it up. You may also find some useful articles here -

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