Box office success refers to the financial performance of a film in theaters, measured by ticket sales. A movie is considered successful when it earns significantly more than its production and marketing costs, often leading to profits for studios and investors. High box office numbers can indicate a film's popularity and audience appeal. Factors contributing to box office success include effective marketing, star power, and positive reviews. Films like Avatar and Avengers: Endgame have achieved record-breaking earnings, showcasing the potential for blockbuster hits. Additionally, timing of release and competition from other films can also impact a movie's box office performance.