The official supplemental textbook for the Networking Essentials course in the Cisco Networking Academy. Networking is at the heart of the digital transformation. The network is essential to many business functions today, including business-critical data and operations, cybersecurity, and so much more. A wide variety of career paths rely on the network, so it's important to understand what the network can do, how it operates, and how to protect it. This is a great course for developers, data scientists, cybersecurity specialists, and other professionals looking to broaden their networking domain knowledge. It's also an excellent launching point for students pursuing a wide range of career pathways - from cybersecurity to software development to business and more. The 'Companion Guide' is designed as a portable desk reference to use anytime, anywhere to reinforce the material from the course.