What is Apache 2 web server and what does it do?

With Apache 2, we are dealing with one of the oldest and for a long time the by far most important web server on the internet. At its peak, the software reached a market share close to 90 percent, with the only significant competition coming from the web server Internet Information Services (IIS) integrated into Microsoft Windows Server. The spread of Apache 2 together with Linux as the operating system is considered a breakthrough for the previously niche and university-known open-source software under various open-source licenses.

Although facing increasing competition from software like nginx for large websites or lighttpd for embedded devices, Apache still maintains its leading position in 2019 with over 30 percent of all active websites. nginx closely follows with just under 20 percent. More information on the current distribution of market shares can be found in our Web Server Overview.

Contents:

Apache 2 - A free web server from the early years of the internet
Rise to becoming the backbone of the modern internet
The .htaccess file - A peculiarity of Apache 2
Advantages and disadvantages of Apache 2 compared to alternatives

Apache 2 - A free web server from the early years of the internet

As the internet transitioned from a scientific and military network to a commercial and public network in the early 1990s, the few available web servers either came from research institutions like US universities or from a few commercial providers. Not surprising - after all, the first click on an HTTP link was only a few dozen months earlier on August 6, 1991. One of the few options was the NCSA HTTPd web server released by the US National Center for Supercomputing Applications (NCSA), which served as the foundation for the project of eight programmers.

The name Apache is derived from a tribute to Native Americans, although rumours often claim it is actually an abbreviation of the English phrase A Patchy Server - a reference to its origins as an extension of NCSA HTTPd. Due to its stability, versatility, reliability, and easy configuration - and not least because of its free availability - Apache quickly established itself as the most important web server of the still young internet. Especially students and small start-ups founded by them, the first digital pioneers, could not afford the extremely high license fees for commercial products like Microsoft Windows with IIS Webserver and opted for the combination of the free Linux operating system with Apache.

Rise to the Backbone of the Modern Internet

Due to its high flexibility, broad support from an interested and competent community, and a steadily growing demand, Apache quickly established itself as the preferred solution for a technically advanced, secure, and stable web server. The software led to some of the most important innovations in the development of the modern internet and established lasting standards in many respects. Some of the most important requirements for a reliable and flexible web server are attributed to the successor Apache 2, which are still considered indispensable today:

• Modular design for flexible functionality extension
• Rules for internal processing of public addresses (Rewrite Rules)
• Support for integrating external scripting languages like Python, Perl, or PHP
• Central and local configuration for different domains
• Speed enhancement through temporary cache storage
• Scalable load balancing for large networks such as CDNs
• Optional support for protocols like FTP or WebDAV
• Integration of more secure cryptography via SSL encryption

Apache reached its maximum popularity in the decade following the turn of the millennium, during which it temporarily achieved almost a monopoly position with a market share of up to 90 percent. However, certain disadvantages, especially in terms of speed under high load and due to a high, native resource consumption, favoured the emergence of alternatives - notably nginx for Content Delivery Networks (CDN) or other high-traffic websites, and lighttpd as a lightweight, efficient, and resource-saving web server for Embedded Devices.

The .htaccess File - A Special Feature of Apache 2

One of the reasons for the high and enduring popularity of Apache 2 as a web server is the opportunity it offers to users through local configuration using a .htaccess file. It is essentially a modular extension that allows rule-based redirection on a hierarchical level. Upon each request, Apache 2 checks this - starting from the lowest directory (Root) - for the existence of a .htaccess file within the file structure. If present, the web server executes the instructions contained within it. Possible applications include:

• Temporary or permanent redirection of specific addresses to other directories or a domain
• Setting up additional protection through password authentication for specific areas
• Converting dynamic URLs into absolute addresses for SEO purposes
• Geoblocking based on IP address
• Access control based on provider, client, time of day, or other parameters
• Rewriting, sorting, and filtering appended parameters

The .htaccess file is one of the foundations for the immense flexibility of Apache 2. Its particular advantage lies in granting users almost unlimited freedom without requiring advanced permissions to manipulate global or local configurations. For individual customisation, simply upload a basic .htaccess file in text form to the corresponding directory, defining the desired rules within it.

Advantages and Disadvantages of Apache 2 Compared to Alternatives

Almost all of the positive features were subsequently adopted by competitors such as nginx or LiteSpeed, but they also eliminated some of the crucial disadvantages of Apache. These become apparent as the number of connected clients increases, as Apache 2's efficiency decreases steadily with numerous parallel connections due to its memory and resource management. The issue is that this effect can be mitigated and distributed through load balancing or a CDN, but not completely eliminated.

Learn more in a detailed comparison of the advantages and disadvantages:

Apache vs. LiteSpeed
Apache vs. Nginx
Apache vs. IIS

Advantages for Apache 2 include its excellent documentation in numerous languages and the unmatched flexibility it provides to users - whether it's for managed web hosting, a dedicated server, or a VPS hosting. The unique concept of the .htaccess file ensures almost unlimited freedom, requiring no special configuration or access beyond the usual permissions. It also allows inexperienced users to set up their own configurations without the risk of a global misconfiguration and compromising other directories.

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