When was the last time you grabbed a box of crayons, opened a coloring book, and let your imagination run wild? These days, there are endless options for coloring books that provide adults with a fun way to explore their creativity. Filled with everything from animals to intricate patterns to pop-culture references, these books have become a revelation and also important relaxation tools. Some really mean it when they call themselves—ahem—“adult,” but many are suitable for all ages, making them excellent activities for parents and their kids, classrooms, or parties. Or, grab a beverage of choices, pick out your favorite set of markers or crayons, and use these books to fill some quality, stress-free, alone time.