Artists use the medium of painting to express emotion and mood through various techniques such as color choice, brushstrokes, composition, and subject matter. They may use warm colors like red and orange to convey passion or intensity, while cool colors like blue and green can evoke feelings of calmness or melancholy. The use of dynamic brushwork or thick impasto can create a sense of energy or movement, while soft, blended brushstrokes may suggest serenity. Additionally, the arrangement of elements within the painting, such as placement of figures or objects, can influence the overall mood conveyed. By carefully selecting these elements, artists can effectively communicate their intended emotions to the viewer.