The Ethereum Virtual Machine has three areas where it can store data- storage, memory  and the stack, which are explained in the following paragraphs.

・Storage - store in persistent storage on blockchain.

・Memory - contract obtains a freshly cleared instance for each message call.

・Stack - all computations are performed on a data area called the stack

possible > move stack elements to storage or memory impossible > to just access arbitrary elements deeper in the stack without first removing the top of the stack. .

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• storage - variable is a state variable on blockchain
• memory - variable is in memory and it exists while a function is being called

stored only during function execution.

• calldata - special data location that contains function arguments
• Stack - **The stack holds those variables which are necessary for immediate processing(**スタックは即時処理に必要な変数を保持します)

contract Example {
	 uint256 thisIsAStack;
}

■ Good Article

Solidity supports three types of variables.

• State Variables − Variables whose values are permanently stored in contract storage.
• Local Variables − Variables whose values are present till the function is executed.
• Global Variables − Special variables exist in the global namespace used to get information about the blockchain. e.g) msg.sender, block.timestamp, block.difficulty