A web server hosts websites by storing and delivering web pages, images, and other content to users’ browsers upon request. It ensures that websites are accessible and performant for visitors worldwide.

Web servers enhance security through features like SSL/TLS encryption, which encrypts data transmitted between clients and servers, protecting sensitive information. They also implement access controls and firewalls to prevent unauthorized access and attacks.

Web servers offer scalability through techniques such as load balancing, which distributes incoming traffic across multiple servers to maintain performance during peak times. Caching and clustering are also used to optimize resource allocation and handle increased workload demands.

Apache and Nginx are popular web server software due to their reliability, performance, and extensive features. Apache is known for its flexibility and support for various modules, while Nginx is favored for its efficiency in handling concurrent connections and serving static content. Both are widely used in different scenarios based on specific needs and preferences.