Keep Your Electronic Communications Really Secure

Q. What are the advantages of using a messenger app like Signal? Does everybody I want to communicate with have to use it as well?

A. Signal is one of several communication apps that fully encrypt the conversations you have with other users. Keeping your exchanges private is the main advantage of using such a program.

Signal encrypts not only text messages but also voice and video calls, pictures, and documents. To benefit from the secure exchange, everyone in the conversation must use Signal, so you may need to persuade your friends to download the app and sign up for the service.

The free, open-source app is available for Android and iOS. Signal also has a desktop edition for Windows, Mac and Linux, but you first need to install the app on your phone and link it to your phone number.

Once you set up Signal on your phone, you can invite your friends to join you. While Signal doesn’t have stickers or some of the more whimsical features of other messaging apps, it does let you create a profile name and an avatar. You can also set messages to disappear after a set amount of time.

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Signal encrypts conversations “end to end” with the Curve25519, AES-256 and HMAC-SHA256 standards, so only your recipients get the messages — and nobody else along the way. Signal’s creators say the company doesn’t have access to the message contents and has placed the app’s source code on a public server for anyone who wants to poke around in it.

WhatsApp is a similar private messaging tool. However, it’s owned by Facebook, which has caused privacy advocates and others to voice concerns based on the company’s troubled track record with handling personal data.

Personal Tech invites questions about computer-based technology to techtip@nytimes.com. This column will answer questions of general interest, but letters cannot be answered individually.