According to Wikipedia: A coloring book (or colouring book) is a type of book containing line art for a reader to add color using crayons, colored pencils, marker pens, paint or other artistic media. Coloring books are generally used by children, though coloring books for adults are also available. They cover a wide range of subjects, from simple stories for children to intricate or abstract designs for adults. The golden age of coloring books is considered to be the 1960s.
People are making the adult coloring books bestsellers on Amazon! At the time of this writing, eight of the top twenty books on the bestsellers list, are coloring books for adults. There must be something behind this recent growth in interest.
The themes of adult coloring books are usually intricate and centered more around adult images, not your childhood counterparts that included bunnies, super heroes, and farm animals. You would expect to see geometric patterns, psychedelic patterns reminiscent of doodle art type pages, fantasy images including angels, dragons, goddesses and mermaids, and ancient designs of religious and spiritual nature.
When you are planning to hold a Sponge-Bob birthday party, try to send the invitations around 2-3 weeks ahead of the party date. Order matching invitations or make your own. Cut a starfish or pineapple shapes from card stock paper.
Best of all of course are free pages that can be printed out at home any time you like. There is so much variety obtainable that as long as they have their pages and something to color with a child will never get bored. For many children, there is no greater gift they can give to Mom or Dad than a picture they coloured all by themselves. Inside or outside of the lines, any page coloured with love and happiness is a masterpiece.
Today the Internet simplified looking for info. And coloring pages took advantage of the Internet progress.