Is scrambling process in which files are made unreadable until the specific decryption method has been employed.
Cryptography is an old science and it has been used for decades by governments and armies around the world to protect their confidential data. Nowadays, cryptography took its place in our computers, allowing ordinary users to use the most advanced algorithms to protect their private files.
Once encrypted, your files would be unreadable. The files can be brought back to a readable state by decrypting.