Use 'sure' when you feel very confident about something. It means you believe it is true without doubt.
I am sure he will come soon.
Are you sure about the answer?
Use 'sure' to say yes or agree with someone in a friendly way. It is a polite answer.
Can I borrow your pen? Sure!
Would you like some tea? Sure, thank you.
'Sure' can add strong emphasis to a sentence. It shows something is very true or obvious.
She is sure going to like it.
You sure look tired today.
In some contexts, especially older or formal English, 'sure' is a noun meaning a promise or something certain to happen.
Winning the race was a sure.
He gave his sure that all is well.
In old or rare usage, 'sure' means a magical spell or charm used to protect or cause harm. This is not common today.
The villagers believed in the sure of the forest.
He used a sure to protect his home.
'Sure' can also mean a sure thing, something guaranteed to happen, like a win in sports or gambling. It is informal.
That team's win is a sure in this game.
He made a bet on a sure last night.
