Full-bodied Muppets require the performer to literally step inside them. Big Bird is probably the most recognizable of this type of Muppet. To attain Big Bird's height, the Muppeteer inside wears shoes with 5-inch heels. He raises his right hand as high as he can above his head to control Big Bird's head and mouth. His left hand fits into Big Bird's left glove. Most of the time, Big Bird's right hand is controlled by a wire that runs underneath the costume and attaches to his left hand. That means that when the Muppeteer raises his (and Big Bird's) left hand, Big Bird's right hand goes down, and vice versa. In performances in front of a chroma key screen (a blue screen or green screen), a second Muppeteer operates Big Bird's left hand.
Originally, Muppeteers saw out of full-bodied Muppets through a scrim in the Muppet's neck, with a small monitor strapped to their chests to watch the Muppet's actions. Advances in technology allow two Muppeteers to operate some large Muppets, like the Gorgs from "Fraggle Rock." One Muppeteer wears the costume and watches movements through tiny monitors embedded inside the head at the Muppet's eye level. The other provides the voice and controls facial expressions remotely.
These are the basic mechanics of Muppeteering, but actually performing in front of the cameras is even more complex. Muppets are especially unique because they don't perform in a traditional "puppet theater" with a curtain or backdrop to conceal the Muppeteer. They walk around like human actors and often interact with the actors. Next, we'll look at how this is accomplished.