This chapter will start with networking solutions used in the past for connecting several branches of a company. Technological advances like broadband Internet access brought about new possibilities and new concepts for this issue, one of them being the Virtual Private Network (VPN). In this chapter, you will learn what the term VPN means, how it evolved during the last decade, why it is necessary to modern enterprises, and how typical VPNs work. Basic networking concepts are necessary to understand the variety of VPN solutions discussed in this chapter.