Introduction Network security is an intricate topic traditionally handled only by professionally trained and experienced persons. Yet, as more and more individuals become connected through computer networks, a rising number of people need to comprehend the fundamentals of security in a networked environment. In the domain of networking, network security comprises of provisions and guidelines established by the network administrator to curb and monitor illegal or unauthorized access, misuse, alteration, or denial of the computer network and other network-based resources (Stallings 2010). Network security comprises of a range of computer networks, both private and public, that are employed in day-to-day tasks such as carrying out business transactions and communication among firms, public and private institutions, enterprises, and persons. Network security does just as its name goes, protects the network and manages all processes being done on the network. Objective The objective of the paper is to expound on network security and its importance in computer networks. Background information on computer networks will also be provided as well as risk management, network threats, firewalls, and hardware and software devices that can be used to improve the security of a computer network. Introduction to Computer Networks An elementary comprehension of computer networks is essential in order to understand the codes of network security. A network is any set of interconnected lines, basing this definition on the current topic, a computer network is basically a set of linked computers. Networks enable users to share resources and information, and are classified base on a variety of protocols (Network Security Threats 2011). For instance, a classification based on the connection manner focuses on the hardware and software systems used to link the individual computer units, such as optical fiber, wireless connection, or coaxial cable communication. Networks can also be categorized on scale, this gives Local Area Network (LAN), wide area Network, virtual Private Network (VPN), among others (Stallings 2010). Networks are made up of ‘nodes’, which are the individual computers in the network, and at least one server and/or ‘host’ computers. The nodes are linked together by communication systems, which may be private, such as that within an institution, or can be accessed by the public, such as the internet. Several private networks also use the internet. The moment a computer network is instituted, it immediately becomes vulnerable to network security threats such as viruses and bugs that may affect the normal functioning of a computer. Besides, the personal information such as usernames, passwords, credit card numbers and other critical information may be at risk if the computer does not have adequate security measures. There are very many threats in a network, some of which are so severe and can bring down a large network consisting of thousands of computers. Virus In the domain of computer networks, a virus refers to a computer program that can replicate itself, similar to the biological virus. A computer virus spreads from one computer to another through an executable program that attaches itself on pr