A cat may purr for a variety of reasons:

Seeking attention: wanting the owner to play with it or touching.

Express needs: such as being hungry, thirsty, or needing to clean the litter box.

Physical discomfort: It may be illness or injury, and the discomfort is expressed by whispering.

Anxiety or nervousness: such as the presence of new surroundings, strangers, or other animals.

Estrus: This is a sign of a cat in heat.

Aging or cognitive problems: This may occur in older cats.