Data location

In Solidity, you have the option to define where your variables will be stored. You can decide to store them in the following places:

• Storage: This is a permanent place that gets written on the blockchain, therefore it's expensive to use
• Memory: This is a non-permanent place where variables are held for only as long as the smart contract is running
• Calldata: This is where the msg object data information is stored, a place dedicated to global variables

An example of this is in the following code:

uint256 memory myNumber;
string storage myText;