Ethereum-Solidity Quiz Q17: What visibility modifiers does Solidity use?

Source: Dev.to

Visibility Modifiers Overview

Solidity uses four visibility modifiers to control how functions and state variables can be accessed:

• public – can be called from within the contract, other contracts, and externally.
• external – can be called from other contracts and externally; not from within the same contract (except via this).
• internal – can be called from within the same contract and derived contracts (inheritance); not from other contracts or externally.
• private – can be called only from within the same contract; not from derived contracts, other contracts, or externally.

Important notes

• State variables can be public, internal, or private (they cannot be external).
• Functions can be public, internal, private, or external.
• public state variables automatically generate getter functions.
• external functions are more gas‑efficient than public because they don’t create an internal function copy.
• private and internal do not provide security; blockchain data is always visible, they only restrict access via function calls.
• Use external for functions intended to be called from outside the contract.
• Use internal for helper functions used through inheritance.
• Use private with caution—typically only for internal helper functions.
• Use public for state variables that need to be publicly accessible.
• Remember that private provides no security; it merely prevents accidental calls.