When building a small business network, the three most essential pieces you will need are connectivity, switches and routers. All 3 provide different functions within a network.
What is connectivity?
A network is essentially a number of devices set up to communicate with each other. This could include computers, printers, mobile phones, iPads and routers. They exchange information with each other, so we can do things that print from any device in the office.
Connectivity is the physical connection between branch offices or to the Internet that allows devices to connect over a wide geographic area or out to the public internet. Without connectivity information can only travel within the local area network (LAN), such as in one office. For businesses wanting to collaborate across multiple locations, or the outside world connectivity such as Internet, MPLS, Metro Ethernet, etc. is essential.
A LAN describes a network with geographical constraints, such as a computer and printer in the same room. WAN (wide area network) covers a much wider distance, allowing devices to talk to each other through a private network that spans multiple locations.
What is a switch?
Switches facilitate the sharing of resources by connecting together all the devices, including computers, printers, and servers, in a small business network. The switch is a box that allows connected devices to share information and talk to each other, regardless of where they are in a building or on a campus. Often data cabling in a building is run to a centralized point and terminated on a switch connecting everything together.
What is a router?
a router connects switches and their associated devices to form an even larger network. These networks may be in a single location or across multiple locations. The router works like a dispatcher, directing traffic and choosing the most efficient route for information to travel across a network.
A router connects your business to the world, protects information from security threats, and can even control which devices or traffic has priority over others.
When building a small business network, you will need one or more routers. In addition to connecting multiple networks together, the router also allows networked devices and multiple users to access centralized servers or the Internet.
Designing your network
Design your network with reliability and redundancy in mind. This will help give you the business continuity you need to recover quickly from unplanned events. Invest in network connectivity and equipment that will allow you to grow over time. 
You want to build a network that scales as your business grows, you can add new features and functionality, such as video surveillance and voice over IP (VoIP), as you need them. The cheapest quick solution will cost your more time, money and frustration so make the right investment the first time.
