...websites are now much more complex than before, and generally require a lot more engineering efforts to be robust and scalable.

One of the biggest challenges for a website architect has always been concurrency. Since the beginning of web services, the level of concurrency has been continuously growing. It's not uncommon for a popular website to serve hundreds of thousands and even millions of simultaneous users. A decade ago, the major cause of concurrency was slow clients—users with ADSL or dial-up connections. Nowadays, concurrency is caused by a combination of mobile clients and newer application architectures which are typically based on maintaining a persistent connection that allows the client to be updated with news, tweets, friend feeds, and so on. Another important factor contributing to increased concurrency is the changed behavior of modern browsers, which open four to six simultaneous connections to a website to improve page load speed.

NginX matters for mobile, especially if you're building an API to serve as the backend for mobile apps (because there are so few mobile apps that are useful without a solid API).

From the NginX chapter of Architecture of Open Source Applications. If you're an engineer who wants to be serious about your work, check this book out.

If you're a business person who wants to be serious about your engineering, call Cloudspace. 407-823-8808.