Gesso is an important art supply to get your canvas ready for painting.Gesso is very similar to white acrylic paint, only thinner. It dries hard, making the surface more stiff. Gesso prepares (or "primes") the surface for painting, making the surface slightly textured and ready to accept acrylic or oil paint. Without gesso, the paint would soak into the weave of the canvas.
The beauty of gesso is that you can apply it to nearly any surface, and then you can paint on that surface with acrylic paint. For example, you can apply a layer or two of gesso to vinyl records, rubber duckies, or cigar boxes, and voila - you can now paint on that object with acrylics! What fun. The possibilities are endless!