A major (also known as a major concentration or concentration) is a term for the specific group of courses that give you a basic knowledge of a field of study, which is in addition to your core curriculum. A major is a term most commonly applied to a program of study leading to a bachelor's degree. The fine and performing arts school will define a framework for this specialized portion of your studies, including a certain number of required courses and a certain number of "elective" courses relevant to the major. The school will also define your general education or foundation education requirements. Some majors in some fine and performing arts schools effectively define your full course of study; many others allow you considerable latitude both within your field of study and in their other courses.
Although many students choose their major before entering a university or college, many others will select it during their first or second year of a three- or four-year program.
Typically, university programs do not allow you to officially declare your major until the end of your second year so that you experience a broad range of courses that will help you choose the most appropriate major. Some majors have limited enrolment so in fact you may even be required to apply to get into the major you want, including attending an interview, audition or submitting a portfolio or essay. Community and career college programs generally do not have majors as such. Their 1- to 3-year diploma and certificate programs carry a designation, for instance Diploma in Visual Art Foundation Studies, which is much more specific than, say, Bachelor of Fine Arts.
Often, students in a community college or career college program--sometimes all the students in the department--will take a common set of core foundational courses in the first year (or term, in the case of shorter programs) which then enables them to pursue a specialized area of study. But generally the field of study at the community or career college level is job-focused to the point where students do not take "elective" courses as they do for bachelor's degrees. Hence the designation of the diploma effectively stands in for the "major."