Traffic filtering is a method used to manage and control the flow of data across a network. It involves examining incoming and outgoing data packets to determine whether they should be allowed through or blocked. This process helps protect networks from unwanted or harmful traffic, such as viruses or malware, ensuring that only safe and relevant information reaches its destination. By using tools like firewalls and intrusion detection systems, organizations can set specific rules for what types of traffic are permitted. This not only enhances security but also improves network performance by reducing congestion caused by unnecessary data.