The purpose of art can be varied. When new visual ideas are first introduced by the artist, they are often shocking. With time the best ideas are accepted.
Let's look at some of the purposes of art.
Likely the oldest purpose of art is as a vehicle for religious ritual. From the prehistoric cave paintings of France, to the Sistine Chapel, art has served religion. For centuries the Church was the primary patron of artists. In traditional societies even today, the primary purpose of art is religious or ceremonial.
The purpose of art may also serve as a commemoration of an important event. The event may also be of major historical importance, for example, the coronation of Josephine by Napoleon. As recorded by the artist David, or it may be important only to the participants. Such as the image of a wedding or a baptism.
Art as propaganda
Another purpose of art has often served as propaganda or social commentary. Propaganda images are attempts to persuade us toward particular viewpoints or actions. Promoted by institutions such as political parties, governments, or religious groups. The propaganda purpose maybe one we approve of, such as World War II efforts or to get women behind the war effort, as in Norman Rockwell's Rosie the Riveter.
The purpose of art may also be something we disapprove of. In either case, the power of images has been used to persuade people to accept beliefs, take action, or follow leaders. The artist may simply make us more aware of the human condition as he/she perceives it.
Art as a record for truth
Art may be simply a means of recording the "truth" about what we see. After the Renaissance, artists became preoccupied with new ways of capturing reality. In time, artists like Courbet and Cezanne (and many who followed them) began in various ways to challenge basic ideas.
The idea of beauty has been challenged in the modern era. At one time, the artist was expected to portray perfection. Yet as society became more industrialized many people began to broaden what could be beautiful. For example, Rembrandt could celebrate the tactile quality of paint and colour in his picture of a side of beef. And Courbet and Millet could see beauty in the life of ordinary peasants.
Art is also a powerful means of storytelling.
This was a common device of religious art of the Middle Ages. For example in the frescoes by Giotto from the Church of San Francesco de Assisi. Sequences of panels are used to tell stories. It is also the gift of Norman Rockwell. Who had the ability to tell powerful stories in just one image. A picture is truly worth a thousand words.
Art can also convey intense emotion. For example, religious art and the works of Munch or Kirchner are charged with emotions. Picasso, in works such as Guernica, is able to communicate intense emotions. Accomplished variously by use of dramatic or exaggerated colour, light, form, and/or other elements.
The purpose of art is as varied as the art and the style itself. For myself part of why I love art is just to show off the beauty of the area and bring attention to Vancouver.