What Are Web Servers? The Backbone of the Internet

Every time you open a website, send an email through a browser, or stream a lecture video, an invisible machine somewhere is quietly doing the heavy lifting. That machine is a web server. It is the silent workhorse that keeps the World Wide Web running, yet most users never think about it. For students of information science, understanding web servers is essential because they are the foundation on which digital libraries, online catalogues, institutional repositories, and almost every internet service are built. This post breaks down what web servers are, how they store and deliver content, the software that powers them, and how they talk to your browser.

What exactly is a web server? 🔗

A web server is a combination of hardware and software that uses HTTP and related protocols to respond to requests made over the web. In simple terms, its main job is to store website content and deliver that content, such as text, images, videos, and applications, to users by storing, processing, and delivering webpages. When people say “web server,” they usually mean both the physical computer that stores the files and the software running on it that handles the requests.

The hardware side is a computer that is connected to the internet around the clock and holds the website’s files, such as HTML documents, CSS stylesheets, JavaScript files, and media. The software side is the program that understands web protocols and knows how to find and send the right file when someone asks for it. A computer that hosts a website must have this web server software installed to store, process, and display content. This pairing is why your browser can fetch a page from a machine sitting thousands of kilometres away in a fraction of a second.

Static versus dynamic web servers 🔗

Web servers come in two broad flavours. A static web server consists of a computer with HTTP server software, and it sends its stored files to your browser exactly as they are. According to MDN, it is called “static” because the files are delivered unchanged. This is fine for a simple page that looks the same for everyone.

A dynamic web server is a static web server plus extra software, most commonly an application server and a database. Here, the content is generated on the spot. When you log into a library account and see your borrowed books, the server is pulling your specific data from a database and building the page just for you. This is made possible through server-side scripting, which runs code on the server to customise the response and generate content in real time. Scripting languages such as PHP and technologies like Active Server Pages allow HTML documents to be created dynamically rather than stored in advance.

How web servers store and serve HTML documents 🔗

At the most basic level, a web server keeps website files organised in directories, much like folders on your own computer. Each file has an address, and the server’s job is to match an incoming request to the correct file and send it back. Understanding this matching process is the key to understanding how the web actually works.

The journey from address to webpage 🔗

When you type a web address into your browser, a sequence of steps unfolds quickly. First, the browser needs to find the real numerical address of the server. It does this through the Domain Name System (DNS), which translates a human-friendly name like a website’s URL into an IP address, or it retrieves the address from its cache. As MDN explains, the browser then sends an HTTP request message to that server, asking it to send a copy of the website to the client.

Once the request reaches the correct hardware web server, the HTTP server software accepts the request, finds the requested document, and sends it back to the browser, again through HTTP. If the server cannot find the requested document, it returns a 404 response instead. This is why the dreaded “404 Not Found” message appears when a page has been moved or deleted. The server checks whether the requested URL matches an existing file, and if it does, it sends that file’s content back to the browser.

Building the complete page 🔗

A webpage is rarely a single file. To display a page, the browser first sends a request to fetch the HTML document. It then reads that file and makes additional requests for the resources the page needs, such as CSS for layout, JavaScript for interactivity, and sub-resources like images and videos. The browser then combines all these resources to present the complete document. So opening one page can trigger dozens of separate requests to the server, all coordinated in the background.

Interestingly, web data does not travel as one large block. Information is broken into small packets, each carrying a header with details such as the source and destination addresses and the total number of packets, along with a payload of actual data. Sending data in small packets is efficient because if one is dropped or corrupted, the client can simply request the missing piece rather than the entire file again.

Popular web server software 🔗

While the concept of a web server is universal, several different software products do the job, each with its own strengths. A handful of programs dominate the market, and knowing them helps when choosing infrastructure for a digital library, an institutional website, or a research repository.

Apache HTTP Server 🔗

The Apache HTTP Server is one of the most widely used and historically important web servers. It is a free and open-source cross-platform web server released under the Apache License 2.0 and maintained by a community of developers under the Apache Software Foundation. First released in 1995, it has been a backbone of the web for three decades. Because it is open source, there are no licensing costs even for large deployments, which makes it especially attractive for educational institutions and startups working on tight budgets.

Apache’s biggest advantages are its flexibility and portability. It runs on Linux, Windows, macOS, and other operating systems, and it supports a wide range of programming languages including PHP, Python, Perl, and Ruby. Its modular design lets administrators add or remove features as needed, and its large global community provides extensive documentation and troubleshooting support.

Microsoft IIS 🔗

Internet Information Services (IIS) is Microsoft’s web server, first released in 1995 for use with Windows. Its biggest advantage is tight integration with other Microsoft offerings, particularly the .NET framework and ASP.NET, along with a polished graphical management console that offers detailed performance reports. It is commonly used to host ASP.NET web applications and static sites, and it includes built-in security and authentication features.

The main limitations of IIS are that it is proprietary rather than free, and it works only in Windows environments. If an organisation already runs Linux servers, IIS is not an option. For institutions deeply invested in the Microsoft ecosystem, however, the seamless integration and vendor support can be worth the cost.

Nginx, LiteSpeed, and others 🔗

Beyond these two veterans, the market has shifted considerably. Nginx (pronounced “engine x”) has risen to the top spot, valued for its high performance and its ability to handle a large number of simultaneous connections efficiently. It often serves static content and also acts as a reverse proxy and load balancer. According to web server usage statistics, Apache and Nginx together command the largest share of the market, with IIS, OpenResty, and LiteSpeed following behind. LiteSpeed is notable because it uses the same configuration format as Apache and is compatible with most Apache features while aiming for speed and a low memory footprint.

Client-server interaction over HTTP 🔗

The conversation between your browser and a web server follows a strict set of rules called HTTP, the Hypertext Transfer Protocol. Understanding this exchange explains how every web service, from a search engine to an online public access catalogue, functions.

The request and response cycle 🔗

HTTP follows a classic client-server model. As MDN describes it, a client opens a connection to make a request and then waits until it receives a response from the server. In web development, the “client” is the web browser, while the person using it is the “user.” The messages sent by the client are called requests, and the messages the server sends back are called responses.

Both requests and responses share a similar structure. There is a start-line describing the HTTP version and either the request method or the outcome of the request, an optional set of headers carrying metadata, an empty line marking the end of the metadata, and an optional body containing the actual data. The body might hold data being sent to the server in a request, or the requested resource being returned in a response.

Status codes and statelessness 🔗

Every response carries a status code that tells the browser what happened. A code of 200 indicates success, while a 404 means the resource was not found, and a 301 signals that a resource has permanently moved to a new location. The web server must answer every HTTP request, at least with an error message, which is why even a broken link gives you a response of some kind.

An important characteristic is that HTTP is a stateless protocol. The server does not keep session data between two requests by default, treating each request as independent. To work around this and remember things like login status, cookies were later added. The server sends a cookie, and the client returns its value with every subsequent request, effectively adding state to the interaction. This is how a website can keep you logged in as you move from page to page.

One trade-off worth noting is that server-side scripting, while powerful, introduces latency because every request from every client must travel to the server before it can be processed. This is why modern web applications often run more code on the client side to keep things responsive.

Why web servers matter for information professionals 🔗

For anyone working with digital information systems, web servers are not an abstract technical detail. Library management systems, online databases, e-resource portals, and digital archives all depend on web servers to deliver content reliably to users. Knowing whether a system runs on Apache or IIS affects decisions about hosting costs, operating system choices, security, and the scripting technologies a team can use. A repository built on open-source Apache, for instance, carries no licensing fee, while an IIS-based system fits naturally into an organisation already using Microsoft tools. Understanding the request-response cycle also helps in troubleshooting, interpreting error codes, and communicating effectively with technical staff.

What do you think? If you were setting up a digital repository for a college library, would you choose a free open-source server like Apache or a vendor-supported option like IIS, and what factors would matter most to you? How might the shift toward dynamic, database-driven web servers change the way libraries deliver services in the years ahead?

References

1. https://www.techtarget.com/whatis/definition/Web-server
2. https://developer.mozilla.org/en-US/docs/Learn_web_development/Howto/Web_mechanics/What_is_a_web_server
3. https://developer.mozilla.org/en-US/docs/Learn_web_development/Getting_started/Web_standards/How_the_web_works
4. https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Overview
5. https://en.wikipedia.org/wiki/Apache_HTTP_Server
6. https://www.upguard.com/blog/iis-apache
7. https://www.comparitech.com/net-admin/iis-vs-apache/
8. https://www.aguko.com/cat/web-servers
9. https://developer.mozilla.org/en-US/docs/Web/HTTP
10. https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Messages