chmod 600 foobar") is not enough in such cases as it can still be read by those with super-user access or with physical access to your storage media (e.g. when your laptop gets stolen or you misplace your backup media). It is also ineffective when you use on-line back-up solutions like SkyDrive, Google Docs or Dropbox. Fortunately Linux provides several tools to help you here depending on your needs.
Some times you need to protect your documents containing sensitive information from prying eyes. Simply enforcing access-control on a document (e.g. "