If Zoom's screen share button is grayed out, the host may have disabled sharing for participants — ask them to go to Security > Allow Participants to Share Screen. If you can click Share but nothing happens or the screen is black: on Mac, go to System Settings > Privacy & Security > Screen Recording and enable Zoom (then restart Zoom). On Windows, try running Zoom as administrator. If the shared screen appears black to others, hardware acceleration might conflict — in Zoom Settings > Video > Advanced, try unchecking "Use hardware acceleration for screen sharing." Close DRM-protected content (Netflix, Disney+) as they force black screens when captured. If you're sharing a specific window and it's blank, try sharing the entire screen instead. Update Zoom to the latest version and restart your computer.