Richard Linklater's "Boyhood" is a coming-of-age story about ordinary people, filmed using a remarkable technique: it took 12 years to complete the movie, with a few scenes filmed every year using the same cast. The main character, a boy named Mason played by Ellar Coltrane, is six years old at the beginning of the film. He's an eighteen-year-old college student at the end, but it's still the same actor. His sister Samantha, played by the director's daughter Lorelei, ages the same way.
It's a powerful technique, far more than a mere gimmick. It's not likely to be repeated any time soon, since it was a huge risk for the studio to gamble on contracting the same actors (including Patricia Arquette and Ethan Hawke playing their divorced parents) over such an enormous period of time, the production kept secret for years. Time slips by in surprising bursts as the movie progresses, without any title cards, fades to black, swelling music, or other cues. One minute you're watching teenage Mason's first magical evening with the girl who has become the love of his life; then you're seeing their final painful conversation a year later, months after they broke up. Once the kids have aged enough to make the passage of time between scenes less obvious, it really keeps the audience on their toes.