Jane Burton / Smoke and silver exotic shorthair Kittens, play-fighting.

Mark Taylor / Two Ginger kittens play-fighting.

Eric Baccega / Ginger Kittens (Felis catus) playing in grass. France, September.

Petra Wegner / Bengal Cats, kittens, 8 weeks, playing together on scratching post.

Mark Taylor / Birman-cross kitten playfully rolling.

Mark Taylor / Two cute tabby kittens, Stanley and Fosset, 7 weeks, playing with a tube.

Jane Burton / Domestic kitten (Felis catus) on basket with another kitten inside it.

Jane Burton / Domestic Cat {Felis catus} Tabby farm kitten playing in straw.

Mark Taylor / Two Ginger kittens playing in a wicker basket

Jane Burton / Two domestic cat kittens play with magnifying glass (digitally enhanced). UK

Mark Taylor / Two Maine Coon kittens playing on a stack of books.

Jane Burton / Domestic Cat, tabby cat 'Popocat' playing with toy mouse