The bar examination is a legal and ethical examination given by each state to prospective lawyers in order to be admitted and licensed to practice law. Several states, including New York and California do not accept bar exams from any other state as qualifications for entrance to be lawyers in those states. Most states, however, accept New York and California exams as sufficient to qualify a law student as "lawyer" in their own state.
The bar exam is, in general, given 2 times a year at a significant cost (usually between 500-2000 dollars) per exam.