Advanced File Vault is one of the most practical, fastest and easiest ways to encrypt your files that you can find. It lets you, with a simple mouse click, place or remove encryption on the file you choose.
Once the encryption is in place, Advanced File Vault automatically assigns it a password. If you want to read that file, you have to insert the corresponding password. To de-encrypt it you just click again.
Advanced File Vault can be applied to any type of file: documents, audio, photos, video, etc.