This approach, characterized by lack of any specific or technical approach to acting, is usually the antithesis of cliché, unrealistic, and so-called "rubber-stamp" acting. Depending on the exact version taught by the numerous directors and teachers who claim to propagate the fundamentals of this technique, the process can include various ideologies and practices such as the extremely notable "what if", "substitution", and "emotional memory".
The modern movement often called method acting is also often referred to as "the Stanislavski System" after Konstantin Stanislavski who pioneered the ideas in his teachings, writings, and acting. His most influential books are the autobiography My Life in Art, and his trilogy of books set in a fictionalized acting school as a pretense for his own teachings, An Actor Prepares, Building a Character, and Creating a Role.
Many others have taken the place of Stanislavski as prominent method teachers. Perhaps the most successful and worthwhile being Michael Chekhov, Anton Chekhov's nephew; Vantankov, a Stanislavski student and protegé; Uta Hagen, the author of "Respect for Acting"; Richard Boleslavski; and most importantly Lee Strasberg who had a great impact on both The Actor's Studio and the Group Theater, which were method acting strongholds, labs for experimentation, and the equivalent to nursery schools for many of the greatest actors of the late 20th century.
A separate, though closely related, school of Method acting was championed by Sanford Meisner, another Group Theatre pioneer. Meisner broke from Strasberg on the subject of "sense memory" or "emotion memory", one of the basic tenets of Method. Meisner's theory thus revolves around being fully in the moment of the character, and experiencing all sensations as the character would, while his contemporaries used their own experiences as springboards into the emotional life of the character.
Though method acting has often been misunderstood or stereotyped to negative effect, causing criticism and even splintering among method acting factions, it remains, as a whole, a successful movement. It allows both creative freedom and room for the individual nature of its participants, but also creates concrete ways of tackling the more abstract portions of the art and fully inhabiting another mind, body and soul.
Valuable books on Method: Respect for Acting by Uta Hagen, An Actor Prepares by Konstantin Stanislavski, To the Actor by Michael Chekhov, or Sanford Meisner on Acting by Sanford Meisner.