강제적이지 않고 본인의 선택에 따라 자유롭게 행하는 방식으로.
In a way that is not required or mandatory; left to one's choice.
예문:
"Users can optionally provide their phone number for two-factor authentication."
"The system allows you to optionally skip the tutorial and start the game immediately."
"You may optionally include a cover letter with your application."