view

A function can read the state (storage variables), but cannot modify it.

Usage:

• You want to access or return values stored on the blockchain.
• No writing or modifying of state happens.

pure

A function cannot read or write to the blockchain state. It is entirely self-contained, like a mathematical function.

Usage

• You don’t need any storage/state variables.
• You’re just computing values based on inputs.
• It only works with local variables or function arguments
• It does not access msg.sender, block.timestamp, storage variables, etc.

function add(uint a, uint b) public pure returns (uint) {
    return a + b; // uses only inputs, not state
}

override

A function overrides a parent contract’s virtual function.

• You inherit a contract and want to change the implementation of a function marked virtual.
• This is part of polymorphism in Solidity's inheritance

contract A {
    function greet() public virtual returns (string memory) {
        return "Hello from A";
    }
}

contract B is A {
    function greet() public override returns (string memory) {
        return "Hello from B";
    }
}

virtual