This white paper includes an overview of the technical building blocks of VPLS, including a review of the MPLS features that help enable the creation of secure customer networks within a shared packet infrastructure. The concept of pseudowires (PW) is covered with a brief description of Ethernet private line service provisioning over an MPLS core. This concept is expanded to a full mesh of PWs, which forms the heart of the any-to-any connectivity of VPLS. The paper concludes with a review of several advanced features, including QoS, Hierarchical VPLS (H-VPLS) and various interworking options.