What is Apache HTTP Server?

Apache HTTP Server is a free, open-source web server software that accepts HTTP requests from browsers and delivers web pages in response. It's maintained by the Apache Software Foundation and has powered a significant portion of the internet since the mid-1990s.

This article covers how Apache works, its key features and modules, how it compares to alternatives like Nginx, and what you need to know to get started with installation.

What is Apache HTTP Server

Apache HTTP Server is a free, open-source web server software that accepts HTTP requests from web browsers and sends back the requested web pages. When you type a website address into your browser, there's a good chance Apache is the software working behind the scenes to deliver that content to your screen. The Apache Software Foundation maintains this software, and it powers everything from personal blogs to massive enterprise applications.

Before going further, let's clear up a common point of confusion. The word "Apache" can refer to three different things: the Apache HTTP Server (the web server software), the Apache Software Foundation (the nonprofit organization that maintains it), and the Apache people (a Native American group from the Southwest). Throughout this article, we're talking specifically about the web server.

Apache plays a central role in what's called the LAMP stack—Linux, Apache, MySQL, and PHP. This combination of technologies has powered dynamic websites for decades and remains popular today.

• Function: Accepts HTTP requests and delivers web content to browsers
• License: Free and open-source under Apache License 2.0
• Maintained by: Apache Software Foundation (ASF)
• Role in web infrastructure: Powers websites ranging from personal blogs to enterprise applications

History of the Apache web server

Knowing where Apache came from helps explain why it became so dominant in web infrastructure.

Origins from the NCSA HTTPd project

Apache traces its roots to the mid-1990s when it emerged as a series of patches applied to the NCSA HTTPd server. NCSA HTTPd was one of the earliest web servers, developed at the National Center for Supercomputing Applications at the University of Illinois. When development on that project slowed down, a group of webmasters started collaborating to improve and maintain it themselves.

How Apache got its name

Here's a fun bit of trivia: the name "Apache" comes from the phrase "a patchy server" because it was originally a collection of software patches. The name isn't a direct reference to the Apache Native American people, though it was also chosen as a respectful nod to the tribe's reputation for endurance and skill.

If you've ever searched for Apache and accidentally typed appache, apche, apatch, aache, apatche, or aoache, you're not alone. These misspellings are surprisingly common.

Major version milestones

Apache has evolved through major versions over the years. The jump from version 1.x to 2.x (currently at 2.4) brought significant architectural changes, not just minor updates. Version 2.0 introduced improved modularity and fundamentally different approaches to handling multiple connections at once.

Key features of Apache HTTP Server

Apache earned its reputation through a combination of reliability, flexibility, and extensive customization options. Let's look at what makes it stand out.

Open source and free licensing

Apache is distributed under the Apache License 2.0, which means anyone can use, modify, and distribute the software without paying a cent. Because the source code is publicly available, developers around the world can inspect it, find bugs, and suggest improvements.

Cross-platform compatibility

One of Apache's strengths is its ability to run on almost any modern operating system. Whether you're using Linux, Windows, or macOS, Apache works consistently across all of them.

Modular architecture for flexibility

Apache's core functionality can be extended through modules, which are add-on components that provide extra features. Think of modules like apps on your phone—you install only what you need. This approach keeps the server lightweight while still allowing for powerful customization.

Support for .htaccess configuration

Apache supports something called .htaccess files, which are directory-level configuration files. In plain terms, these files let you change how Apache behaves for specific folders on your website without touching the main server settings. This feature is particularly useful in shared hosting environments where you don't have access to the main configuration.

Virtual hosting capabilities

Virtual hosting allows multiple websites to run on a single server. Apache supports two types: name-based virtual hosting (where multiple sites share one IP address) and IP-based virtual hosting (where each site gets its own IP address). Most websites today use name-based hosting since IP addresses are a limited resource.

SSL and TLS encryption support

Apache provides solid support for SSL/TLS encryption through a module called mod_ssl. This encryption is what puts the "S" in HTTPS and keeps data secure as it travels between browsers and servers. Today, HTTPS is expected by both users and search engines.

URL rewriting with mod_rewrite

The mod_rewrite module lets you change how URLs appear to users. Instead of showing something ugly like page.php?id=123, you can display a clean URL like /products/widget. This matters for both user experience and search engine optimization.

How the Apache HTTP Server works

At its core, Apache manages the back-and-forth communication between a web browser and a server. Understanding this process helps clarify what the software actually does.

The request-response cycle

The process works like this: First, a user's browser sends an HTTP request to the server, asking for a specific resource like a web page or image. Next, Apache receives this request and figures out how to handle it. If it's a simple file like an image, Apache finds it and sends it back. If it's something dynamic like a PHP page, Apache passes the request to the appropriate processing engine. Finally, Apache sends an HTTP response back to the browser containing the requested content.

Multi-processing modules explained

Apache uses something called Multi-Processing Modules (MPMs) to handle multiple connections at the same time. These modules determine how the server manages incoming requests.

• Prefork: Creates a separate process for each connection. Very stable, but uses more memory.
• Worker: Uses multiple threads within each process, allowing more connections with less memory.
• Event: An evolution of Worker that's optimized for keeping connections open efficiently. This is the default in modern Apache installations.

Configuration files and directives

Apache's behavior is controlled through configuration files, with httpd.conf being the main one. Inside these files, you'll find directives—specific instructions that tell Apache how to operate. For example, a directive might specify which port to listen on or where to find website files.

Advantages of using Apache

Apache has remained popular for good reasons. Here's what draws people to it.

Extensive documentation and community

After nearly three decades of development, Apache has accumulated extensive documentation and a massive global community. If you run into a problem, chances are someone else has already solved it and posted the answer online.

Flexibility through modules

The modular design means you can build exactly the server you need. Running a simple static website? Keep it minimal. Need advanced caching, security, or proxy features? Add the relevant modules.

Wide hosting provider compatibility

Almost every web hosting provider supports Apache out of the box. This widespread compatibility makes it easy to find hosting and deploy websites without worrying about server software compatibility.

Proven stability and security

Apache has a long track record of stability in production environments. The active community provides regular security patches, and the software has been battle-tested on millions of servers over the years.

Limitations and disadvantages of Apache

No software is perfect, and Apache has its drawbacks too.

Performance under high traffic loads

Under extremely high traffic with thousands of simultaneous connections, Apache's traditional architecture can consume more memory and CPU resources compared to newer alternatives like Nginx. This becomes noticeable mainly at very large scale.

Memory usage considerations

Depending on which MPM you use, each connection might require its own process or thread. The prefork MPM, for instance, creates a separate process for every connection. At scale, this memory usage adds up quickly.

Configuration learning curve

Apache offers an enormous number of configuration options, which can feel overwhelming for beginners. The same flexibility that makes it powerful also makes it complex to master.

Apache vs Nginx and other web servers

When choosing a web server, Apache and Nginx are the two names that come up most often. Here's how they compare.

Feature	Apache	Nginx
Architecture	Process/thread-based	Event-driven
Configuration	.htaccess support	Centralized config only
Static content	Good	Excellent
Dynamic content	Native module support	Requires external processors
Learning curve	Moderate	Steeper for beginners

Architecture and performance differences

The fundamental difference lies in how each server handles connections. Apache traditionally uses a process-based or thread-based model where one process handles one connection. Nginx uses an event-driven, asynchronous architecture where a single process can handle thousands of connections simultaneously. This makes Nginx more efficient for serving static content and handling many concurrent connections.

Configuration philosophy comparison

Apache allows distributed configuration through .htaccess files, which is convenient when multiple users share a server. Nginx requires all configuration to happen in centralized files, which can be more efficient but less flexible for shared hosting scenarios.

When to choose Apache over Nginx

Apache tends to be the better choice for shared hosting environments, situations requiring .htaccess configurations, or when you want native processing of dynamic content through modules like mod_php. Many organizations also choose Apache simply because their team already knows it well.

Common Apache modules you should know

Modules extend Apache's capabilities. Here are some of the most important ones.

mod_ssl for HTTPS security

This module enables SSL/TLS encryption, allowing your site to serve content over HTTPS. It's essential for any website handling sensitive information or wanting to rank well in search engines.

mod_rewrite for URL management

This module handles URL redirects and rewrites. It's what allows clean, readable URLs and proper redirect handling when pages move.

mod_proxy for reverse proxy setup

The mod_proxy module lets Apache act as a reverse proxy, forwarding requests to backend application servers. This is useful for load balancing, improving security, or integrating different technologies behind a single entry point.

mod_security for application protection

mod_security is an open-source Web Application Firewall (WAF) that helps protect web applications from common attacks like SQL injection and cross-site scripting.

How to install Apache HTTP Server

Getting Apache running involves a few straightforward steps.

1. System requirements and preparation

Before installing, make sure your system has a supported operating system, enough memory (512MB minimum for basic use), and network access.

2. Installation on Linux systems

On Linux, package managers make installation simple. On Debian or Ubuntu, the package is called apache2. On CentOS or RHEL, it's called httpd. A single command typically handles the entire installation.

3. Installation on Windows systems

For Windows, you can download installers from official Apache partners. For development purposes, many people use bundles like XAMPP, which packages Apache together with MySQL and PHP.

4. Verifying a successful installation

After installation, open a web browser and navigate to http://localhost. If you see the default Apache test page, everything is working correctly.

Who uses Apache HTTP Server today

Despite the rise of alternatives like Nginx, Apache remains one of the most widely deployed web servers in the world. You'll find it running corporate intranets, e-commerce platforms, content management systems like WordPress and Drupal, and countless shared hosting environments. Its longevity speaks to its reliability and the trust organizations place in it.

Powering your technical teams with the right tools

Just as Apache provides a reliable foundation for web infrastructure, organizations benefit from reliable tools to manage and develop their workforce. Platforms like Engagedly help technical teams track performance, foster professional development, and maintain engagement. Book a demo to see how Engagedly supports high-performing technical teams.

FAQs about Apache HTTP Server

Is Apache HTTP Server still widely used today?

Yes, Apache remains one of the most popular web servers globally. It powers websites of all sizes, from small blogs to large enterprise applications, thanks to its reliability and extensive feature set.

What is the difference between Apache HTTP Server and the Apache Software Foundation?

Apache HTTP Server is a specific web server software product. The Apache Software Foundation (ASF) is the nonprofit organization that oversees its development, along with many other open-source projects like Hadoop, Kafka, and Spark.

Can Apache web server handle high-traffic websites?

Apache can handle high-traffic websites when properly configured with appropriate MPMs and caching modules. However, event-driven servers like Nginx may offer better performance for sites with extremely high numbers of concurrent connections.

Why is it called Apache and is it related to the Apache people?

The name comes from "a patchy server," referring to the patches applied to the original NCSA HTTPd code. While not directly related to the Apache Native American people, the name was also chosen as a respectful acknowledgment of the tribe's reputation.

What are common misspellings of Apache?

Common misspellings include appache, apche, apatch, aache, apatche, and aoache. All of these refer to the same Apache HTTP Server software.