---
title: "Method ID"
description: "A brief introduction to Method ID on Ethereum."
url: https://info.etherscan.com/what-is-method-id/
tags: ["Tutorials"]
published: 2023-09-25
updated: 2026-06-21
---

# Method ID

#### What is a Method ID?

Ethereum relies on a unique identifier, known as a Method ID or a function selector, to differentiate between different functions or methods within a smart contract.

Method ID is the first 4 bytes of the Keccak-256 hash of the function signature that specifies which functions to be called. The function signature includes the function name and its parameters' types which are separated by a single comma, with no spaces in between.

![](https://info.etherscan.com/what-is-method-id/images/2023/09/image-37.png)

Example of a Keccak-256 hashed function signature

The Method ID for the function signature is the first 4 bytes (or the first 8 digits) of the Keccak-256 hash.

For functions of contracts that have been verified on Etherscan, the function name will be displayed in the 'Method' column in [Transactions page](https://etherscan.io/txs).

![](https://info.etherscan.com/what-is-method-id/images/2023/09/image-38.png)

Retrieve the corresponding Method ID by going to:

> Transaction details page > Input Data field

![](https://info.etherscan.com/what-is-method-id/images/2023/09/image-39.png)

We automatically match functions for an unverified contract with known functions from verified contracts on Etherscan by comparing bytecode using a process called Similar Match.

As a result, the Method ID displayed for this function may not be 100% reliable.

![](https://info.etherscan.com/what-is-method-id/images/2023/09/image-40.png)

The Method ID is derived from known functions of verified contracts on Etherscan

For unidentified functions, the Method ID is displayed instead:

![](https://info.etherscan.com/what-is-method-id/images/2023/09/image-41.png)

💡

Learn how to easily [filter](https://info.etherscan.com/advanced-filter/#2-method) for all transactions on Ethereum involving a specific Method ID.

#### Method ID Collision

Since only the first 4 bytes of a hashed function signature are used, Method ID collisions have a possibility to occur.

For example, the Method ID [`0x00000000`](https://etherscan.io/txs) may represent more than one function signature:

![](https://info.etherscan.com/what-is-method-id/images/2023/09/image-42.png)

Source: www.4byte.directory

Trolls or malicious actors may use these collisions to fool you. Always be mindful of this when browsing Methods on Etherscan!