The aim of this work is to demonstrate the safety of wireless local area networks. Protection and security are on the rise due to the increasing use of wireless local area networks. The purpose of this work is to show something generally about computer networks and standards of computer networks and different methods of protection and security of wireless computer networks. The focus of the study is on the local and foreign literature on the computer networks. The work presents various methods of protection throughout history protection, their characteristics, advantages, and disadvantages of these methods. From built-in protection mechanisms, user authentication, MAC and IP filtering to encryption keys. Encryption keys are specified by WEP encryption, WPA encryption, to the best and the latest WPA2 encryption methods. The work also contains the stimulation of a wireless computer network made by the Cisco Packet Tracer. This shows a method to protect wireless computer networks via WPA2 mode protection. This work shows the importance of protection and security of wireless local computer networks.