The world would be very different if there were no cats. u003cbru003eu003cbru003eMice and rats would run rampant, and the ecosystem would be thrown off balance. u003cbru003eu003cbru003eCats play an important role in controlling these populations, so without them, we would see a significant increase in these pests. u003cbru003eu003cbru003eAdditionally, cats provide companionship and love, so their absence would be felt by many people.