A window, not a screen

Every screen-sharing tool starts from the same idea: take a picture of the whole display over there and put it in a window over here. It works. It also means you spend your day inside a window within a window, with someone else's menu bar under your own and a Dock you cannot use.

Beam starts from a different idea. The unit is the window. You pick one app on the other Mac, and that app's window opens on the Mac in front of you. It has its own size, its own place on your desktop, its own Dock icon, and it shows up in ⌘ Tab like anything else you have open.

What that changes

A beamed window is not a picture you look at. It is a window you use. Drag a corner here and the real window resizes over there. Type into it and the keystrokes land in the app, shortcuts included. Toggle the speaker and the app's audio plays on this Mac, and only that app's audio.

The picture is streamed at your display's exact resolution, so text stays crisp. There is no scaling to fit, because there is no desktop to fit. One window, at the size you gave it.

• Its own size. The window is as big as you make it, not as big as the other Mac's display.
• Its own place. It sits next to your other windows and moves with your Spaces.
• Its own Dock icon. Switch to it the way you switch to anything.

What the other Mac sees

Nothing. While you work in a beamed window, nothing moves on the other Mac's screen. Someone sitting at it sees the desktop they left. That is what makes Beam usable on a Mac someone else is also using, and on a Mac that has no display at all.

Only the window you picked is shared. Hidden windows and password managers never reach the picker, on either side, so there is no way to beam something by accident.

The honest tradeoff

One window at a time is a constraint as much as a feature. If what you want is to see a whole desktop, with every window in the arrangement you left it, that is screen sharing's job and it does it well. Beam is for the case where you know which app you want, and you want it here, now, as a window you can work in.

Most of our own days are that second case. The build on the Studio. The logs on the mini. The song playing in the other room. Each one a window, and none of them a screen.