What is an Apache server?

Apache controls interactions between web servers and browsers, enabling users to find web pages, HTML pages, images, text, videos and other kinds of content on the Internet. Released first in 1995, Apache played a critical role in the early development of the Internet, allowing people everywhere to build and host their own websites.

The Apache Software Foundation (ASF) manages Apache. This nonprofit organization regularly updates the software to address a wide range of issues, including security, compatibility with new technologies, troubleshooting and more. Apache’s ability to quickly deliver static and dynamic content and power complex user interactions makes it a market leader in web hosting.

Today, Apache is one of the most popular web servers available. Many companies use Apache to power their core business processes and ensure that their website and web applications flourish. According to a recent report by W3Techs, a little more than a quarter of the world’s websites (26%) rely on Apache for their hosting needs.¹

Web servers are systems that deliver web content to users over the Internet. Typically a combination of hardware and software, they can handle user requests for a wide range of content, including images, text, videos and more. Together with application servers, which are servers that enable business applications, web servers have become an important part of the core business functions of many modern enterprises.

Web servers function like a bridge between clients and the World Wide Web. They enable data to be transferred through a series of protocols like Hypertext Transfer Protocol (HTTP) and Hypertext Transfer Protocol 2 (HTTP/2). The web server waits for a client request—for example, entering a web address into the address bar on a web browser—and responds with content.

In Apache environments, the program that runs in the background and facilitates these requests is known as a “daemon” and is referred to as an HTTPd (Hypertext Transfer Protocol daemon).

Most modern web servers are designed to generate dynamic content, like personalized recommendations, advertising and even dashboards that users can customize. To accomplish this task, they are built to be compatible with a wide range of programming languages, including PHP, Perl, Python and more.  

The Apache web server is built to facilitate communication between a web browser (commonly known as the “client”) and the server where a website’s files are kept. Its fundamental purpose is to process requests for content by delivering web pages, HTML, CSS and more through a web browser. Essentially, the software that underpins Apache acts as a middleman, constantly listening for user requests and responding with content.

Apache's approach to handling client requests and generating content sets it apart from other web servers in several important ways.

Another important aspect to Apache server functionality is design. Apache is a critical part of modern web application stacks—also known as tech stacks— which are collections of hardware and software tools that run modern web applications. Apache is a core component of LAMP (Linux, Apache, MySQL, PHP), one of the most powerful and widely used tech stacks on the market.

Here's a closer look at each of LAMP’s components: 

• Linux: Linux is the world’s most popular open source operating system (OS), responsible for managing the resources and applications in all LAMP use cases.

• Apache: In a LAMP tech stack, Apache listens for and processes incoming HTTP requests, relying on Linux to control hardware and software resources.

• MySQL: MySQL is one of the most popular and effective open source relational database management systems (RDBMS) for managing data in a structured format. In a LAMP tech stack, Apache relies on MySQL to help power its dynamic content and applications.

• PHP: PHP is a scripting language on the server-side that integrates with Apache in LAMP use cases and helps to generate dynamic web content.

Apache’s primary function is to respond to client requests with content—a core capability of all websites and web applications. It has a broad range of features and capabilities that enable this functionality.

Unlike proprietary web servers, released by companies like Microsoft, Google and Oracle, Apache is an open source software. In other words, it is free and supported by a large community of experts. Even commercial uses of Apache are free, and developers are constantly modifying its code to fit a unique business purpose.

When new technologies like artificial intelligence (AI) and generative AI (gen AI) change how enterprises create and store content, the open source community is quick to respond, ensuring Apache remains compatible.

Apache is compatible with many kinds of platforms, including Linux, Unix, Windows and MacOS. Its modular architecture, an approach that prioritizes flexibility and customizability, enables new features and functionalities to be added quickly and easily.

For example, IBM’s AIX systems, favored by large enterprises, often deploy Apache in challenging environments. Apache’s open source approach ensures it can be easily integrated into AIX and constantly iterated on as new technologies and use cases arrive.

Apache is ideal for the practice of virtual hosting, which is running multiple websites on a single server instead of a dedicated server for each instance. Apache’s virtual hosting is cost-effective and highly scalable, enabling enterprises to manage multiple domains without extra costs and quickly spin up virtual instances as needed.

Apache offers two approaches, depending on an organization’s compute environment and specific needs.

• IP-based virtual hosting: Each hosted site has its own unique IP address.

• Name-based virtual hosting: Multiple websites share the same IP address and distinguish themselves just through their hostnames.

Organizations can configure Apache by adjusting its encryption and authentication settings and how it uses firewalls, an approach known as Apache configuration.

• Encryption: Apache server supports SSL/TLS (Secure Sockets Layer/Transport Layer Security) encryption protocols, a set of cryptographic protocols that govern how computers communicate over the Internet. Apache allows users to customize their level of encryption in each instance by using a module known as mod_ssl.  

• Authentication: Apache supports a wide-ranging set of powerful authentication and authorization tools that allow users to monitor and restrict resources. Examples include advanced password protection, IP address allowlisting, LDAP (Lightweight Directory Access Protocol) and more.

• Firewalls: Apache can be configured to use different kinds of firewalls according to the needs of a specific compute environment. ModSecurity, for example, is an open source web application firewall (WAF) that helps protect sensitive web applications from cyberattacks aimed at the application layer.

Apache server’s load balancing capabilities allow it to optimize resources during high-traffic situations on popular websites and applications. It can distribute client requests across different servers so no single server receives too many requests, slowing down functionality and performance.

Apache servers are also effective at caching, storing and reusing frequently requested pages to reduce the workload on servers and effectively manage bandwidth. Apache can also function as a reverse proxy, a server that acts as an intermediary between other servers and client requests, helping optimize performance and resource distribution.

Apache compares favorably to other kinds of web server software, primarily due to its modular design, open source nature and compatibility with other platforms and technologies. While it no longer enjoys the dominance it did in the late 1990s and early 2000s, it is still considered a strong option for various web and web application hosting needs. Here’s a look at how it stacks up against its two closest competitors: NGINX and Microsoft IIS.

NGINX (pronounced engine-x) recently overtook Apache as the most popular web server in the world, with 33% of the market share according to a 2025 report.²

The biggest difference between Apache and NGINX is in their architecture: Apache server uses a process-driven architecture that creates a new process called a thread for each client request. Alternatively, NGINX employs an event-driven architecture, enabling it to handle many requests concurrently in the same thread.

NGINX is also slightly faster than Apache at serving static content due its more efficient caching capabilities. In terms of serving dynamic content, NGINX uses external processors, like PHP-FPM for PHP, whereas Apache processes dynamic content internally, on the server-side.

Microsoft IIS is another popular web server that, like Apache, was designed to host websites and web applications and serve content in response to user requests. Unlike Apache, Microsoft IIS is a proprietary solution built specifically to work with other Microsoft software solutions and support. One of the strengths of Microsoft IIS is that it simplifies development and deployment for .NET and ASP.NET frameworks—widely used environments for building web applications.

For enterprises running sites and applications on Windows servers, Microsoft IIS is a strong solution, offering straightforward and powerful integration with other Microsoft tools like Active Directory and Exchange Server. It is also known for its easy setup and management and simple, straightforward graphical user interface (GUI).

Due to its wide range of features, open source nature, security features and compatibility with new technologies, Apache has many enterprise use cases. Here are a few of the most common.

• Websites and web applications: Apache’s compatibility with the most widely used scripting languages in the world, like Python and PHP, makes it a preferred choice for hosting websites and web applications. Many content management systems (CMS) like WordPress and Drupal are powered by Apache, as well as CRM applications like Salesforce. Also, many of the top-performing media and news sites, such as The Guardian and Spotify, also rely upon it.

• Enterprise applications: Apache is considered a strong choice for hosting complex, demanding enterprise applications, software systems designed to facilitate the core operations and business processes of large organizations. It supports many of the top financial services apps, data analytics platforms and e-commerce sites used by the world's most successful companies. Walmart, for example, relies on Apache to facilitate the thousands of daily transactions on walmart.com and provide a seamless user experience.

• Content: Apache helps the world’s largest organizations serve content to their large user bases, including static web pages, images, video and more. Apache optimizes performance, responding to client requests within seconds and managing web resources to ensure lightning-fast loading times for sites and applications.

• Intranets and internal websites: Many organizations rely on Apache to host their intranets and internal websites, private, secure networks that allow employees inside organizations to safely and confidentially share data and resources. Apache can be easily configured to serve only content within a specific network, ensuring tight access controls and a wide range of customizable security options.

• DevOps: Apache plays an important role in modern DevOps environments, underpinning many critical capabilities. Apache servers often act as reverse proxies, load balancers and backend servers for complex, demanding web applications that developers rely on.