I. Context and Background

Before you start tinkering with your systems, you need to think things through. You need to set policies or at least think a bit about security. That requires some knowledge about security related concepts. This part introduces you to a number of these concepts and provides most of the information you need to be able to find the proper balance between safety and usability for your systems. After reading this part you will be able to set a security policy and know the implications of that.