To learn about GPG:
On most web browsers, you can right-click this link: sample.gpg
The sample file is encrypted with GPG using the password: secret
To decrypt the file on a Unix or MacOS command line:
gpg -d sample.txt.gpg > sample.txt
For technical people, the command we use to encrypt the file is:
gpg -c --cipher-algo aes256 --digest-algo sha256 --cert-digest-algo sha256 --compress-algo uncompressed