Hard is both an adjective and an adverb. When it is an adverb, it means ‘needing or using a lot of physical or mental effort’. It goes after the main verb:
I studied hard for my exams but didn’t do very well.
We have worked hard all day.
The comparative and superlative forms are harder and hardest:
He didn’t get into the team this year. He’ll just have to try harder next time.
Not: He’ll just have to try more hard next time.
Right, children, who has worked hardest today?
Don’t confuse hard with hardly. Hardly usually means ‘only just’ or ‘almost not’:
Every day I ran a lot and worked hard so that I would be prepared for the game.
Not: Every day I ran a lot and worked hardly.
