Art has a diverse set of purposes.
Some people would say that art is the expression of culture (not only the artifacts of a culture but the articulation of the ideas that define a society).
Some people would say that art allows people to express the contents of the human mind and spirit.
Others would say that art is a mode of communication. Art is a means to identity definition. Art is an attempt at finding and expressing the truth of experience.
The purpose of art is self expression. It is a way to show someone's feelings and emotions. It can make a political statement, a religious statement or even a whimsical statement. Art is very personal and evokes different feelings in different people. To one person, a painting may be breath-taking and to another, it is simply offensive. Sometimes art isn't understood or appreciated right away and must be viewed several times or even over many years, before its greatness is recognized.
Art is simply another medium for the same kinds of expression of the human condition found in prose, poetry, drama, music, and dance and any other form that is classified as fine arts. It is a visual field that communicates through image, perspective, line, color, dimension. Different media in art can be used such as oil on canvas, etchings, lithographs, sculpture, etc. Art is just different forms of the messages of the human soul.
Art allows expression of the individuality of the artist. Through artistic endeavors, people can share what is important to them with others and can learn about the values of feelings of those sharing art with them. This is what makes art a hallmark of human activity - the thoughts and emotions behind artistic expression, in whatever medium the artist chooses as most appropriate for displaying his/her talents, are unique to the human species. We are driven to incorporate forms of art into our surroundings in ways that are unknown to other forms of life on earth.
For me, the viewing of art is aesthetically pleasing--an arousal of the senses and emotions that will differ with each example and with each viewer. Likewise, the quality of the individual piece will elicit different feelings to each observer. The quality of art extends to many forms, including music, sculpture, painting, architecture and furniture. Different types of music will conjure up various feelings and memories, especially to the sense of hearing, while three dimensional pieces may entice more than just one of the senses (sight and touch). It is this human experience that best exemplifies the purpose of an artistic endeavor.