Turn Off File Sharing

If you are using a MacBook and take it out of the house/workplace at all, be sure to turn off System Preferences, Sharing, File Sharing. There’s nothing wrong with turning it on to use it occasionally, and then off again when done, though AirDrop is a better option nowadays. But if you have it on and aren’t using it, your Mac will show up in Finder sidebars of other Macs connected to the same hotel/coffeehouse/airport Wi-Fi network.