Protection via Encryption

 Sometimes you wish to protect data on your compute devices by more than permissions and ownership. Encryption may be the method chosen.

 BE AWARE encryption is a double edged sword. If you lose or forget the key, you will have the same problem accessing your data that you are wanting to use to thwart others.

 So, what are some options?

 Security by obscurity. Name the file with an benign name. Change the extension to prevent default application from opening. 
e.g. squash recipie rename from resume.doc

For windows and MacOS you can adjust permissions on files and folders so others can not read or modify those files and folders. There are many ways to overcome such settings. Slightly more protections of the intended data than obscurity.

You can also "hide" files and folders so others will need to expend more effort to "find" the hidden data. 
Windows: attrib +h +s path\filename 
MacOS:  chflags hidden path/filename
Linux: add a leading dot "." to the filename

You can encrypt documents/spreadsheets/presentations and other data in most office suites. Select the desired document and use the office suite utilities to encrypt and decrypt the desired data. 
AGAIN, if you lose control of the encryption key or passphrase you will lose access to the data you are intending to protect. Also, the encryption used by most office suites are more easily broken by tools on the Internet.

You can purchase external media that has encryption capabilities. 
Size, connection methods, encryption strength, capabilities, and other factors will influence that purchase. 

Bio-metrics for encryption key control is also a double edged sword. Finger print enablers are better for loss of encryption key control, but not if you lose that finger or you need to have the data passed to an heir or spouse.

Full disk encryption can protect a drive on the compute platform you want to protect via encryption. If your platform is stolen or you lose physical control then the drive will need the encryption key or passphrase to access the data.

A more controlled approach is to use encryption applications or utilities to provide protection via encryption.

TrueCrypt was the popular encryption app for many years. Open source, flexible, dependable, free. VeraCrypt is the current fork of the TrueCrypt utility. 

Other encryption utility offerings include DiskCryptor, Cryptainer LE, and Challenger.

Users needs vary. One should determine their needs and use the above and other options to fit those needs. If your needs change, revisit the options available at that time.

These methods offer a level of data protection. As with most things, you need to protect the protections.