Signal is easy to use, works on both iOS and Android, and encrypts communications so that only the sender and recipient can decipher them.

It also has open source code, meaning it can be inspected to verify security. You can download Signal from the Android Play Store and the iPhone App Store.

Although Signal is well-designed, there are extra steps you must take if you want to maximize the security for your most sensitive conversations — the ones that could be misinterpreted by an employer, client, or airport security screener; might be of interest to a snooping government, whether at home or abroad; or could allow a thief or hacker to blackmail you or steal your identity.

I discuss these steps at length below, in order of importance. If you wish to jump ahead to a specific section, you can click the appropriate link: