Nginx (pronounced engine x) is open source Web server software that also performs reverse proxy, load balancing, email proxy and HTTP cache services. The software was originally created by Igor Sysoev as an answer to the challenge of handling 10,000 concurrent user connections: the C10k problem.
Nginx provides high performance for Web servers with massive scaling. Nginx is able to run at high speeds under heavier loads. The reverse proxy feature allows a single site to present aggregated information sources as if they all come from one page. Its load balancer allows loads to be split among different resources such as servers.
Many prominent companies use Nginx to manage high-traffic pages, including Autodesk, Facebook, Atlassian, LinkedIn, Twitter, Apple, Citrix Systems, Intuit, T-Mobile, GitLab, DuckDuckGo, Target, Intel, Microsoft, IBM, Google and Cisco.
Part of the reason Nginx scales so effectively and runs faster than other Web server software -- such as the standard Apache build -- is its more efficient use of processes. Unlike Apache builds, Nginx does not create a process per user. Nginx instead uses a master and worker process structure. The master process controls the worker processes which perform the calculations.
Nginx is important because it was purposely built for extreme loads and efficiency. The Web server software helps a number of aspects of hosting Web site applications and content delivery services. Nginx is the second-most popular Web server software after Apache.
F5 Networks currently owns Nginx, having purchased it for $670 million in March 2019. The software is distributed with a BSD-like license. Nginx is free but was offered also as Nginx Plus with paid support.