What does calligraphy and painting mean?

Add a bottom plate to the back of calligraphy and painting. Calligraphy and painting backing is to add a bottom plate on the back of calligraphy and painting, which can protect and support the works. For the collection value of calligraphy and painting, the backing itself will not directly affect its value, but more depends on the quality of calligraphy and painting, the author's popularity, historical background and market demand.