To be alive is to be engaged in communication, politics, power, and art inherently is a reflection of that fact. All things, even the element of lacking or missing pieces can be considered art. Always collectively created not just by the maker, rather the work is completed upon encountering a willing receiver.
However, it is the very act of processing, comprehension and reflection filtered via the individual's perspective constructed and encoded entirely by the society, time and culture in which they exist. Making it both intangible yet defined solely by its direct connections and unique ephemeral context.
Art is not only a noun but a verb, both transitive and intransitive, despite all the efforts of capitalists to relegate it to the role of mere objects.
Thereby delineating itself in the form of any object, or image that assigns meaning, or functions as a call to action. A "successful" piece relies on finding your receivers, and perhaps persuading new ones to engage. It will also expose the people who do not want to be reached by you, or worse those who want you dead. Art has often focused on the power to create community but I also find it to be one of the greatest tools to reveal your enemies. Most importantly art is a free and potent weapon against tyranny and injustice.