Like a Russian doll, every cinematic technique contains smaller techniques within it. There is no one technique, for instance, called “the close-up.” There are extreme close-ups, in which you can see every pore on a character’s face. (Think of Tom Cruise’s perspiring visage in Mission: Impossible.) Alternately, there are medium close-ups, in which we are allowed to watch a character thinking, but we don’t feel we’re barging into personal space.

The long take, similarly, must be qualified. There’s the long take a la Orson Welles in A Touch of Evil, in which the camera twists and turns, the viewer’s tension slowly building as we wonder, "where are we being taken?" Or there’s the long take of Goodfellas, for instance, which amounts to a celebration of an entire demimonde, frolicking at the Copacabana Club; by the end of it, you feel as if you’ve met everyone in the room.
There’s also, as this thoughtful and wise video essay by Nathan Shapiro shows, the long take of Alfonso Cuarón.

In this interpretation of Cuarón's technique, this focus is less on the camerawork in the scene than on what we can learn about characters by simply looking at them for a while. The camera follows the action, but Cuarón’s goal is not so much to draw attention to the camera as a tool as to show us something about characters’ interactions and personal history—something about what we might call their chemistry.

In Y tu Mama Tambien, one very long take shows us the growing relationship between Luisa and her two teenaged escorts; in Harry Potter and the Prisoner of Azkaban, a long take shows us the developing confidence between Harry Potter and a mentor; in Children of Men, one particularly long take builds tension as the protagonists run through a war zone, bombs falling and shots firing all around them.

And as if that weren’t enough, consider the 17-minute long take that opens Gravity. As we watch an astronaut spinning through space, the hapless victim of flailing machinery, we find ourselves wholly empathetic. Cuarón’s approach demonstrates that the long take can help to develop a story’s underpinnings even as it makes a film more thrilling to watch.