hard vs hardly

Hard describes the intensity or effort of an action, while hardly indicates that an action almost never happens or barely occurs.

• hard

  with great effort or intensity

  The team worked hard all weekend to finish the project before the deadline.

• hardly

  scarcely, barely, or almost not at all

  The music was so quiet that I could hardly hear the lyrics.

• Wrong: She studied hardly for the exam but still failed the most difficult section.→Right: She studied hard for the exam but still failed the most difficult section.

• Wrong: I have hard any money left in my bank account after paying rent.→Right: I have hardly any money left in my bank account after paying rent.

Hard is for effort; hardly is for 'almost not'.