Computer networks exist in most businesses today. A well planned and implemented computer network allows for quick, reliable communication among management, staff and customers, as well as the ability to share resources (data, printers etc) and centralize data for an easy backup strategy.
The benefits of email and internet access can streamline many of your business processes (i.e. Internet banking), but the drawbacks (Viruses & Cryptolocker malware) also need to be considered.