Richard Linklater’s “Boyhood” is the ultimate coming-of-age narrative in any media. Being the last word on the subject, all past and future attempts to depict the maturation from the childhood to young adulthood will seem fundamentally incomplete.

Because “Boyhood” is nothing if not a complete film. You probably know the story of this buzziest of movies by now: Linklater began shooting the film in the summer of 2002, when his lead actor, Ellar Coltrane, was 7. They returned every following summer, for 12 years, shooting this 164-minute epic two weeks at a time. As a result, we watch everything get a little older and, yes, wiser: the actors onscreen, the technology they use, the conversations in which they engage. Linklater has called “Boyhood” a period piece, but it hardly meets the definition of one; he never recreates an older period but shoots forever in the now, filling his movie with the magic of the immediate moment, the majesty of the everyday.

The pioneering documentarian Michael Apted attempted a similar film experiment with his career-long “Up” series, revisiting the same group of kids every seven years and charting their transformations into adolescence and middle age. Francois Truffaut famously followed his onscreen surrogate, Jean-Pierre Leaud’s Antoine Doinel, over a 20-year period. And Linklater himself, ever the patient auteur, has taken a groundbreaking long view with his “Before” trilogy, charting the development of a chatty pair of lovers over a real-time, 18-year trajectory.

Both of these ongoing projects look glacially paced compared to “Boyhood,” which moves at an addictively propulsive pace. Each year in Mason’s (Coltrane) life spans about 15 cinematic minutes, then cuts to the next year without warning and waits for us to catch up to its characters’ sometimes slight, sometimes profound differences in age, height, demeanor and bodily wear and tear.

Despite its professional editing and production values, its spirit is akin to a compilation of home movies, where a person’s evolution and eventual self-actualization is observed through a graduated timeline of significant annual moments, each intended to stand in for the other 50 weeks a year we miss. It’s the movie equivalent of one of those Darwinian flipbooks, where the monocellular organism becomes a reptile, then a primate, then a Neanderthal, then a millenial tapping away on an iPad.

You’ll be astonished at the consistency of character, as the director and most of the actors, dividing their time between other projects over a dozen years, become themselves so fully, as if no time passed at all. Tellingly, this is a movie, like the “Before” trilogy, that is largely about the ephemerality of time itself, its endless forward motion: We’re just beginning to grasp what Mason’s life is like in any given year, and whoosh—we’re already in the next one. How true is this sensation? It’s the perfect movie for anyone who’s ever had the thought, “I can’t believe another year has gone by,” or “they grow up so fast, don’t they?”

This would normally be the point in the review that I would fill with a plot description, but when dealing with a plotless character study like this, the task seems provincial and beside the point. There are so many captivating surprises in this movie—so many instances of relatable laughter and equally relatable, heart-in-your-throat tragedy—that to mention any of them would be to spoil the wonder. I’ll speak instead of the wonderful acting. Linklater’s daughter Lorelei plays Mason’s older sister, Samantha, and her transformation is just as remarkable as Coltrane’s; you’ll find yourself wishing the director and his cast had shot enough material for “Girlhood,” shooting a second epic from Samantha’s point of view.

Patricia Arquette and Ethan Hawke play the children’s divorced parents, Olivia and Mason Sr. As the years move inexorably onward and Olivia’s number of ill-fated husbands increases, her hair style and mannerisms become ever more matronly, her mistakes ever more glaring, her intentions ever purer (at one point, I scribbled the note “she’s doing the best she can;” minutes later, she says the same line in a defensive argument with Samanatha). Mason Sr., and Hawke himself, grows up slower, maintaining his youthful rakishness until his body acquiesces to age. By the end, he’s become the movie’s elder statesman, its longtime slacker who, no less than his son, has finally accepted manhood.

As for Coltrane, his work here is astonishing, the sort of the emotionally vulnerable, naked performance only achieved by actors who have shed all notions of self-consciousness and can make the camera disappear. Whenever he cuts through the bullshit of the movie’s hypocritical authority figures—whether it’s his parents, his employers, his monstrous stepfathers—he doesn’t even have to say anything: You can read it in his eyes.

Even when some of these figures are right, we side with Mason, because we’re invested in him, not his guardians, and they all come off as hindrances to his life path. We want to see him finally liberated, free of his nest and ready to find himself. We’ve all been there, whether or not we’ve had overachieving older siblings or divorced parents or violent stepfathers, or were bullied in school or harangued by teachers. The movie feels more authentic than most documentaries, each scene a brief, inspired burst of lightning in a bottle.

And like many of the best films in movie history, “Boyhood” is also about film itself—about celluloid as a preserver of the past and a harbinger of the future. This being 2014, I thought everything in movies had been done, every narrative innovation explored. “Boyhood” proves me wrong. I can already say with utmost confidence that this will be remembered as the best film of the year, if not one of the greatest in the history of the medium.

“Boyhood” is currently screening at the Broadway Centre Theatre. Click here for showtimes.