We live with films every day, and it seems nothing easier than answering the question: what is a film? Obviously, a film is, first and foremost, a document, a testimony of the world that surrounds us. The rich expressional possibilities of film are based on the imperfection of the human eye, its sluggishness, so thanks to the stroboscopic effect we can animate a still image. Film is therefore a kinetic image, or a moving image. It can make the invisible visible, bring the distant closer, enlarge the small, speed up the slow, slow down the fast, and return the end to the beginning. The technological basis of film: light, film tape, camera, projector, film screen. Expressive possibilities of film: scientific, documentary, communicative, artistic. Basic film genres: differences among films.