I bought this book at the recommendation of one of my fellow colorists in a group for adult coloring books enthusiasts in Facebook, and it is just WONDERFUL! It is a twist on coloring by number - you pick your own colors, numbered 1 through 5, with 1 being the darkest, then increasingly lighter for 2, 3, 4, and 5. You can't tell what the picture is going to be unless you look in the back of the book - you just see a bunch of different-sized circles with numbers 1 through 5 in some of the circles and intersections among the circles, and the picture appears as you do the coloring! I have tried using realistic colors and they are fine but I think I am getting to like using colors that look well together, whether or not they are colors used in the actual art painting. And it is just GREAT that this is an oversized book, 13.8" x 9.8" to show off your masterpiece! I, myself, like using Bic and Sharpie markers, using both the fine tips (to fill larger spaces) and same color ultra fine tips (for the smaller spaces). I like them because they are nice rich, colors, and they fill medium to larger areas easier and more smoothly than gel pens or water-based markers. You do have to watch for feathering - the paper is a good quality and the Sharpies and Bic markers don't feather as readily as on less quality paper. But if you pause, you do get blotches and some light feathering, so you need to move along as you are coloring. I, myself, like to draw around the shape of the numbered circles and intersections, and then color them in keeping to the curve of each circle. The Sharpie and Bic markers fill in even large areas very well, but you can also faintly see the shapes of the circles underneath. I think this adds to the finished look which includes the colored numbered circles as well as some circles purposely left blank. It's amazing what a realistic image you get that clearly looks like the work of art, such as the Mona Lisa, pictured on the cover. Enjoy! This is a GREAT book to color!