Activity is a noun that refers to the state of being active or the condition in which things are happening or being done.
Common usages of activity include:
1. Physical activity - any bodily movement that requires energy expenditure
2. Business activity - operations related to commerce and trade
3. Social activity - interactions between people in a social setting
4. Volcanic activity - the state of a volcano being active
5. Classroom activity - tasks or exercises done in an educational setting