You may not have used them, but your phone and computer come with a variety of options for quickly beaming files between devices without getting Wi-Fi or the internet at large involved. The idea is that users can quickly transfer data from one device to another, or share files with family and friends in a convenient way.
Like many other tools, though, the convenience and ease of use of these systems also mean they're open to abuse—and you really don't want random, unwholesome photos being sent your way by strangers on the subway. Here's how to configure these sharing features so you can make use of them and stay protected too.
Apple's favorite device-to-device sharing protocol is called AirDrop, and you'll find it used extensively in the software that runs on your iPhone or iPad: It's a really easy way to send files between Apple devices that shows up whenever you hit a share button.
To control who can and can't send you files over AirDrop, go to Settings, then pick General and AirDrop. You have three options here: Receiving Off (stop anyone from sending you files), Contacts Only (only people listed in your Apple contacts can send you files), and Everyone (anyone can send you files, a setting we wouldn't recommend).
You can find the same three options in Control Center if you press and hold on the panel with the airplane mode, Wi-Fi, Bluetooth, and cellular options in it. A larger panel will appear, and you can then tap AirDrop to make your choice.
It's worth mentioning that even if you leave your AirDrop access open to anyone, you'll still have to specifically accept any files that are sent your way via a pop-up dialog. Still, that's a risk that's probably not worth taking, just in case you accidentally accept something you don't want to.
AirDrop actually relies on Bluetooth, which itself can be used as a more primitive way of sending and receiving files. If you want to disable both file transfer methods at once, go to Bluetooth in Settings and turn the toggle switch off.
You can't limit the connections that can be made via Bluetooth like you can with AirDrop: Your phone or tablet is either visible or it isn't. However, if another device tries to connect to yours (potentially to send over files), you'll see a pairing confirmation dialog that you can dismiss to block the link.
Android has cycled through various AirDrop-style approaches of its own down the years, but the most recent one is called Nearby Share. It's an Android-to-Android file-sharing system, though it isn't available on all handsets.
If you have Nearby Share, you can find it by opening up Settings then choosing Google and Device connections. From this screen, tap Nearby Share to configure how the feature operates: If you don't want to use it at all, you can turn it off completely using the toggle switch at the top.
Assuming you do want to make use of Nearby Share, you can select Device visibility to pick one of three options: All contacts (anyone in your Google contacts list can send you files), Some contacts (only the contacts you specify in a list can send you files), and Hidden (no one can send you files).
The three settings above come with caveats. No matter what setting you use, anyone will be able to send you files if they turn on Nearby Share and you also turn on Nearby Share—this will show as a Tap to become visible notification on your phone. If you ignore that notification, no one can see you.
Even if you do decide to become visible to anyone nearby, any attempted file transfer will prompt another confirmation dialog box. This applies to files sent by approved contacts as well, so there's at least one and sometimes two pop-ups to get through before you'll find yourself accepting a file from someone else.
As on iPhones, Bluetooth is another option for file sharing on Android, but you will have to accept a pairing request and a file transfer prompt before data can be sent over. You can't control this in as much detail as Nearby Share, but you can turn Bluetooth on or off via Connected devices then Connection preferences in Settings.
The options for macOS are fairly similar to those for iOS and iPadOS: AirDrop is here, as you would expect, and can be customized as needed. Open a window in Finder, and you'll see the AirDrop link in the navigation pane on the left—click on it to see your AirDrop transfers and settings.
At the of the AirDrop tab, you can click Allow me to be discovered by to select from No One (no one can see your Mac), Contacts Only (only your Apple contacts can see your Mac), and Everyone (anyone using AirDrop can see your Mac). As on mobile devices, if your computer can't be seen, files can't be sent to it; if your computer can be seen, you'll still need to approve any attempted file transfers.
Bluetooth is another option for sharing files on a Mac. Open the Apple menu, choose System Preferences, and then select Bluetooth to turn it on or off. As on phones, for someone to be able to send you a file, you'll need to have Bluetooth on, and accept their pairing request, and accept the file transfer.
Windows has its own computer-to-computer file-sharing protocol called Nearby Sharing (almost the same as Android's chosen name). It can only be used between Windows computers, but it's a convenient way of getting files sent over. You'll find it in Settings under System and Shared experiences.
Under Nearby Sharing, you'll see a toggle switch to turn the feature on or off, and the drop-down menu underneath offers two options: Everyone nearby and My devices only. You might want to keep this set to the latter option unless you know someone wants to share something with you, but even if you opt for the former, any connection requests will still need to be approved by you.
As on all our other devices, Bluetooth is here as well. From Settings click on Devices then Bluetooth & other devices to enable or disable it. If you don't use any Bluetooth accessories, you might decide it's safer to leave it off, but even if it's on someone else will need two approvals to send you files: One to pair their device over Bluetooth and one to accept the file transfer.