Call controls, chat and shortcuts
The controls sit along the bottom of the call. On a phone, the ones that do not fit are under More options.
The control bar
Mute microphone and Stop camera. With your camera off, the others see your profile picture in a circle, or your initial if you have none.
Raise hand shows the others that your hand is up, until you press Lower hand.
Send reaction floats an emoji up the screen for a few seconds, with your name.
Messages opens the conversation beside the call, or over it on a phone.
Share screen and the layout button are covered in the article on screen sharing and layouts.
The members button lists the people in the conversation, and is where the host lets people in.
Settings is described below.
Hang up leaves the call.

While you wait alone in a call between two people, you have only the microphone, camera, members, Settings and Hang up buttons. The others appear once the other person arrives.
You see your own camera mirrored, as in a mirror. The others see you the right way round.
Messages during a call
This is the same conversation you see in Messages, so everything sent here stays there after the call. You can reply, react and share files, including by dragging them onto the open Messages panel. When a message arrives while the panel is closed, it pops up for a few seconds and a red dot appears on Messages.

Settings
Audio: the microphone to use.
Video: the camera to use, and Background blur.
Accessibility: Theme (Light, Dark or Auto) and Font size.
Shortcuts: the keys below.

Sound plays through your device's default speaker or headphones. To use different ones, change the output in your device's sound settings.
Keyboard shortcuts
M microphone on or off
V camera on or off
H raise or lower your hand
L next layout
F11 full screen (your browser's own)Shortcuts do nothing while you are typing a message. On a Mac, use your browser's own full-screen button instead of F11.