A web server stores, processes, and delivers web pages to clients, typically web browsers, over the Internet or an intranet. Here’s a detailed explanation of what a web server is and how it works:
What is a web server?
- Hardware Aspect: A web server can be a physical computer that stores web server software and website files (e.g., HTML documents, images, JavaScript files, etc.). When someone requests a web page, the web server delivers the requested files to the user’s browser.
- Software Aspect: A web server can also refer to the software that runs on the physical server and delivers web content. Examples of web server software include Apache HTTP Server, Nginx, Microsoft Internet Information Services (IIS), and LiteSpeed.
How do web servers work?
- Client Requests: The process starts when a client (usually a web browser) requests a web page by typing a URL into the browser’s address bar or clicking a link.
- DNS Resolution: The browser sends a request to a Domain Name System (DNS) to translate the human-readable domain name (e.g., www.example.com) into an IP address, which is the web server’s address where the website is hosted.
- TCP/IP Connection: Once the IP address is obtained, the browser establishes a TCP (Transmission Control Protocol) connection with the web server using the IP address. This involves a TCP handshake, where the client and server acknowledge their communication readiness.
- HTTP Request: After establishing the connection, the browser sends an HTTP (Hypertext Transfer Protocol) request to the web server. This request can be of various types (GET, POST, PUT, DELETE, etc.), with GET being the most common for requesting web pages.
- Processing Request: The web server receives the HTTP request, processes it, and determines what action to take. This might involve fetching an HTML file, executing server-side scripts (e.g., PHP, Python, Ruby), or querying a database to retrieve dynamic content.
- HTTP Response: Once the requested content is ready, the web server returns an HTTP response to the client. This response includes a status code (e.g., 200 OK, 404 Not Found) and the requested content (e.g., HTML document, image, etc.).
- Rendering Content: The client’s browser receives the HTTP response, processes the content (e.g., rendering HTML and CSS, executing JavaScript), and displays the web page to the user.
Additional features and concepts
Static vs. Dynamic Content:
static content: directly served as stored, such as HTML files, images, and videos.
Dynamic Content: Generated on the fly based on server-side code and database queries.
Security: Web servers use protocols like HTTPS (HTTP Secure) to encrypt data between the client and server to protect sensitive information.
Load Balancing: In high-traffic situations, load balancers distribute incoming requests across multiple servers to ensure reliability and performance.
Caching: Web servers can cache frequently requested resources to reduce load times and improve performance.
Virtual Hosting: A single web server can host multiple websites using virtual hosting, allowing one server to serve different domains.
Common Web Server Software
Apache HTTP Server: A widely used open-source web server known for its robustness and flexibility.
Nginx: An open-source server often used for high-performance serving and as a reverse proxy.
Microsoft Internet Information Services (IIS): Microsoft web server software created for use with the Windows NT family.
LiteSpeed is known for its high performance and low resource consumption.
A web server is a critical component of web infrastructure, facilitating communication between clients and servers by delivering web content efficiently and securely. By understanding how web servers work, one can better appreciate the underlying processes that enable the seamless browsing experience we often take for granted.
