The benefits of coloring books for kids cannot be overestimated. It's not just entertainment, which can permanently keep the child interested, but also gives some free time for parents to make all necessary household chores; it is also an excellent developing material. Combining a game and a hobby such «coloring pages» will help improve the child's imagination, develop creative skills, visual memory and fine motor skills that will prepare a child's hand for the writing skills.
It is believed that the company The McLoughlin Brothers (en.wikipedia.org/wiki/McLoughlin_Brothers) invented the coloring books. They published a book called The Little Folks' Painting Book in collaboration with Kate Greenaway in 1880.