A load balancer in web hosting functions to distribute incoming traffic across multiple servers, ensuring no single server becomes overwhelmed. This is crucial for maintaining high availability and performance of web applications. By intelligently routing user requests based on predefined algorithms, such as round-robin or least connections, load balancers can optimize resource utilization and enhance response times. They also provide redundancy, improving fault tolerance and scalability as traffic fluctuates. In essence, load balancers are essential components for managing server loads efficiently, ensuring a smooth user experience and reliable web service delivery.