How do I share my screen on Zoom, and can I share just one window instead of everything?

Click the green 'Share Screen' button in the toolbar. Instead of 'Desktop/Screen 1' (which shows everything), select the specific app window, PowerPoint, a browser tab, whatever, and only that appears. Attendees never see your desktop, other windows or notifications. Tick 'Share sound' (bottom-left of the dialog) if you're playing a video, and 'Optimize for video clip' for smooth playback. You need to be the host, or the host must allow it (Security > Allow participants to Share Screen). Hit 'Stop Share' when done. Pro tip: turn on Do Not Disturb first so nothing pops up mid-present.

Share the specific WINDOW, not the whole screen, that's the trick to hiding your desktop and notifications. Zoom lists every open app in the share menu; pick just the one you need.

If the Share button is greyed out, the host has locked sharing. They need to go Security > Allow participants to Share Screen, or make you a co-host.

Always tick 'Share sound' if there's audio in what you're showing, otherwise everyone watches a silent video and wonders why. Easy one to forget.