Digital Security 101 - Files Encryption

Veracrypt↗: this app is available for Windows, MacOS and Linux. You don't even have to install it, just download the portable version↗ and execute it. It won't install any file nor archive and it's fully functional. With Veracrypt anyone can create a container file with a strong password. The program offers different levels of encryption depending on the threat model. Once created the container, it must be mounted and a new drive will be displayed. That's the vault in which all your files will be saved fully encrypted.

Picocrypt↗: it's also cross-platform and FOSS. Download the suitable file for your OS and run it. It will display a little window, drag and drop the file(s) there, then write a strong password, confirm it and voilà! Your file(s) will be encrypted.