The primary function of network segmentation is to improve security and performance by dividing a computer network into smaller, isolated sub-networks, or segments. This approach restricts access to sensitive information, minimizing the risk of unauthorized access or data breaches. By limiting the exposure of critical systems and resources, network segmentation also helps contain potential security incidents, making it easier to detect and respond to threats. Additionally, it can optimize network performance by reducing congestion and facilitating more efficient traffic management.