A WAN (Wide Area Network) is the largest private network available. It's made up of multiple LANs (Land Area Networks) and/or MANs (Metropolitan Area Networks). Since private networks stay off the public internet, businesses can securely connect headquarters with branch offices and other facilities. WANs allow businesses to privately send data and voice transmissions without concern of someone hacking via the Intenet. A data center or a dedicated colocation server facility can also be connected to a WAN, and can therefore connect the entire private network to the Internet with only a few firewalls. The Internet is the largest WAN, but since it is open to the public, it is not private.

A WAN is capable of speeds up to 150 Mbps while a LAN is capable of up to 1000Mbps. A WAN has to connect LANs through a shared T1 or T3 line which decreases bandwidth allocation. The shared line also needs special technologies to secure privacy through long distances, which can get expensive. WANs also need specialty equipment and monitoring from WAN Service Providers.

A WAN is not only the physical line. It is also made up of networking hardware, software, and other technologies. An example of a networking technology is MPLS which helped make WANs faster and less expensive. MPLS uses short router adresses in a VPN, designed to get from one network site to another, thereby lessening the call on router databases. A SD-WAN (Software Driven WAN) is a culmination of technologies that replace expensive routers and make the network development and expansion much faster and cheaper.

SD-WAN providers can replace expensive WAN routers with software/hardware combinations in the parts of the network that do not require the full capablities of the router. SD-WAN can be software only, or a combination of hardware and software. Versitility is found in SD-WAN's ability to give it's customers exactly what they require and no more. As the customer's needs change at any site in the network, SD-WAN can adapt.