Nearly everything we access online involves a web server. From reading an article, checking email, or streaming a video, web servers are the foundational technology that delivers digital content to your device. But what exactly is a web server, and how does it work?
In this article, we’ll explore what a web server is, how it operates, its types, components, and why it plays such a critical role in web browsing.
What is a Web Server?
A web server is a computer system or application that stores, processes, and delivers web content (like web pages, images, videos, etc.) to users. When you type a URL into a web browser, that browser sends a request to the web server, which then retrieves the requested content and serves it back to the browser. Web servers can deliver content to any internet-connected device, including desktops, laptops, smartphones, tablets, and even IoT devices.
Web servers play a vital role in hosting websites and handling millions of requests per second across the internet. They function based on protocols like HTTP (Hypertext Transfer Protocol) and HTTPS (HTTP Secure), which define how messages are formatted and transmitted.
How Do Web Servers Work?
Web servers operate through a client-server model, where:
- The client (e.g., a web browser) initiates a request for content.
- The server processes the request, retrieves the required files, and sends them back to the client.
Here’s a high-level overview of what happens when you use your browser to view a webpage:
- DNS Lookup: When you type a website URL, the browser initiates a DNS lookup to find the IP address associated with the domain name.
- HTTP Request: Once the IP is obtained, the browser sends an HTTP/HTTPS request to the web server at that IP address.
- Server Processing: The web server receives the request, locates the requested resources, and processes any scripts or database queries if required. To this extent, the web server may communicate with another server (e.g., a database server) in order to retrieve everything it needs.
- Response Delivery: The server sends back an HTTP response that includes the requested content. This content is in the form that a web browser can understand and render.
- Rendering on the Client Side: The browser receives the response and renders the content for the user.
Web servers are designed to handle multiple requests simultaneously, often using threading or asynchronous techniques to manage load efficiently.
Types of Web Servers
Web servers can be broadly categorized based on their functionality and architecture:
Static Web Servers
A static web server is a web server which is designed to serve static content only. This includes files such as .html, .js, .css files. It doesn’t include content that requires further processing, such as .php, .cfm files, which are written using server-side scripting languages.
- Function: Deliver pre-existing HTML content without processing.
- Use Case: Simple websites where content does not change dynamically.
- Advantages: Fast and efficient; requires less processing power.
Dynamic Web Servers
A dynamic web server is one that can generate content dynamically. This often means pulling data from databases and using server-side scripting to present the user with customized content. Server side scripting can be done using languages such as PHP, Python, ColdFusion, etc.
Typically, a dynamic web server is a web server that uses a plugin to support the specific server-side scripting language. For example, IIS can be configured to handle PHP requests by installing the FastCGI module and adding a handler mapping for .php to the path to php-cgi.exe.
- Function: Generate content dynamically, often pulling data from databases and using server-side scripting.
- Use Case: Websites with frequently changing content or content in a database (e.g., news sites, social media, and any website that uses a CMS).
- Advantages: Can deliver personalized, dynamic content; enables complex functionality.
Application Servers
Application servers typically deliver more complex content from databases, services, and enterprise systems.
- Function: Hosts applications and performs more complex tasks like processing business logic.
- Use Case: Online transactions, complex web applications (e.g., e-commerce sites, messaging systems).
- Advantages: Provides enhanced processing power and integration with databases and other applications.
The line between dynamic web server and application server can be a bit blurry these days, as both can can fulfil many of the same tasks.
Components of a Web Server
The term “server” is often used to describe the physical computer, but the term also has a more specific meaning. A server can also refer to the software. So the term “web server” can refer to the physical machine itself, or it can refer to the software.
Web server software is specialized software that is designed to host websites and serve up web pages and other content. This runs on top of the operating system (which is usually considered to be a server in its own right). And all of this runs on a physical machine.
Here’s a basic breakdown of these components.
Hardware
A web server’s hardware consists of many components. However, some of the most likely things you’ll want to evaluate when building a web server would be things like storage, CPU, and memory.
Not only will you need to have enough resources to cover your normal expected usage, you’ll also need to ensure that the web server has enough resources to cover any spikes in activity that might occur.
Operating System
As with any computer, a web server has an operating system. Popular operating systems for web servers include Linux, Windows Server, and Unix.
The operating system provides the environment where the web server software operates. Sometimes the web server software comes bundled with the operating system.
Web Server Software
Web server software is software that processes requests, manages connections, and serves content to clients. It’s whole purpose is to perform that role.
Popular web server software includes Apache, Nginx, and Microsoft IIS.
The web server software you use will largely depend on the operating system. For example, if you’re using Windows Server, then you’ll likely use IIS. On the other hand, many Unix/Linux based operating systems use Apache.
Server-Side Scripting
Many websites rely on server-side scripting language to handle dynamic content, execute logic, and interact with databases to provide personalized responses.
Server-side scripting languages include PHP, Python, ColdFusion, etc.
While these languages can provide enormous value by facilitating advanced functionality, they’re not a requirement for a web server. It’s entirely possible to have a website that doesn’t use such languages. You could easily create a website with static HTML pages that don’t use any scripting language at all (whether server-side or client side). However, most of today’s websites rely on scripting languages to provide the level of functionality that web users have come to expect.
Database
Databases store and manage data that dynamic websites retrieve and present as part of the content. While database management systems (DBMSs) are often installed on a separate machine altogether, they can also be installed directly on the web server machine.
Having the database server on the same machine as the web server is not always an optimal setup when it comes to factors like performance and security, but it’s often the most appropriate choice for those on a budget with basic needs and low to modest traffic expectations.
Popular DBMSs include MySQL, PostgreSQL, and Microsoft SQL Server.
Web Server Software and Examples
Several web server software options are available, each with unique features, strengths, and typical use cases.
- Apache HTTP Server:
- Most widely used, open-source, highly configurable, and stable.
- Good for both static and dynamic content.
- Mainly used on Linux, but can also be run on Microsoft Windows, OpenVMS, and a wide variety of Unix-like systems.
- Nginx:
- Known for its efficiency, especially under high traffic, with event-driven architecture.
- Excellent at handling static content, often used as a load balancer or reverse proxy.
- Microsoft Internet Information Services (IIS):
- A robust solution for Windows-based environments, closely integrated with .NET applications.
- IIS is included with Windows Server (although you will need to enable and configure it first).
- LiteSpeed:
- Optimized for high performance, popular for its speed and security features.
- Presented as an Apache alternative that conserves resources without sacrificing performance, security, or convenience.
- Can load Apache configuration files directly.
- Can be used with any control panel that was designed for Apache, including cPanel, Plesk, and DirectAdmin
Common Use Cases for Web Servers
Web servers are utilized across various industries for different purposes. Here are some of the main ones:
- Hosting Websites: From personal blogs to large e-commerce sites, web servers make web hosting possible.
- Serving APIs: Many applications use web servers to provide APIs for other applications and services.
- Web Applications: Web servers power applications like online banking, email, streaming, and social media.
- IoT Device Management: Many IoT platforms rely on web servers to manage and exchange data with connected devices.
- File Sharing and Storage: Some web servers are configured for secure file sharing, data storage, and cloud-based document access.
Summary
Web servers form the backbone of our digital experiences, ensuring that content is delivered quickly, securely, and efficiently. Whether you’re building a personal blog, a business website, or a large-scale application, a reliable web server is a fundamental requirement.
From handling HTTP requests and managing user connections to communicating with backend processes, web servers are central to almost everything we do online. As the internet continues to grow, web server technology will keep evolving to meet the demands of faster speeds, better security, and more dynamic content.