How can I stay safe on a shared or public computer?

A computer you do not own - at a library or hotel, or a friend's desk - is fine for casual browsing, but it can quietly hold on to your logins, and you cannot know what software is running on it. A few habits let you use one without leaving your accounts behind.

The risks

Saved logins. Browsers offer to remember passwords and keep you signed in. On a shared machine, that hands the next person your accounts.
Recorded keystrokes. A public computer could be running software that records what you type, passwords included.
Over-the-shoulder. In public, people nearby - or cameras - can watch you type a PIN or password.

Safer habits

Use a private or incognito window so nothing is saved, and never accept "remember me" or an offer to save the password.
Sign out of every account when you finish, then close the browser.
Keep banking and anything truly sensitive for your own device.
Shield the keyboard when you type a password or PIN.
Afterwards, from your own device, sign out remotely if you can - most accounts list where you are signed in and let you remove sessions.

If you're lending your own device

Logging out is not the same as handing over a clean slate - your saved passwords, email, and history may still be reachable. Set up a guest account (both Windows and macOS have one) and let them use that: they get a clean, empty session, and when they log out it disappears. It protects them too, since anything they open by accident is contained. Using guest mode is not a sign of distrust - it is just tidy.

If you only do one thing

Use a private window, and sign out of everything before you walk away. Keep banking for a device that is yours - and when you lend your own, let people in through a guest account.