Which tool is commonly used to manage and filter network traffic in cybersecurity?

A firewall is a crucial tool in cybersecurity that manages and filters network traffic. It acts as a barrier between trusted internal networks and untrusted external networks, allowing or denying data packets based on a set of security rules. Firewalls can be configured to allow specific types of traffic, such as web browsing or email, while blocking potentially harmful traffic, such as that from malicious sources. This capability is essential for protecting networks from unauthorized access and attacks.

In contrast, an intrusion detection system focuses on monitoring network traffic and identifying suspicious activities or policy violations, rather than controlling traffic flow. While encryption software is vital for protecting data by transforming it into a secure format, its primary role isn’t to filter or manage traffic but to ensure confidentiality. Similarly, an anti-virus program is designed to detect and eliminate malware on individual devices, rather than overseeing and regulating traffic across a network. Therefore, the firewall's primary function of managing and filtering network traffic makes it the most suitable choice for this question.