It's important to acknowledge the relevance of web development, and not only specifically to frontend development. Today, nearly every kind of software we build can be developed using web technologies, and target virtually every platform.

It's amazing how JavaScript has penetrated the industry and, it has certainly been a game changer ever since. Using web technologies, you can write complete backend systems, including microservices and serverless architecture styles, while using your preferred protocols and patterns, such as REST, GraphQL, and WebSockets. It doesn't stop there either: web technologies are relevant for IoT, VR, OpenGL, and even databases!

Focusing on frontend web development, what is a web app really?
When people hear the term web apps, they usually think about apps that run in the browser. However, that has not been the case for a long time now. Web technologies enable you to target multiple platforms such as desktop and mobile, and possibly even share a code base between these platforms.

Web development is one of the most popular and in-demand fields today, but how did that come to be?
Historically, in the desktop era, before the age of smartphones, people primarily used their desktop machines to use applications and browse the web, as those were simpler times. Later, the explosion of devices took place. Smart devices emerged onto the market and were widely used. Nowadays, people have numerous devices, and not just one; everyone is connected — all the time, everywhere.

Typically, businesses want to build software and reach as many users as possible, which usually implies targeting multiple platforms. Building platform-specific software is not a simple task. It has vast implications for time and cost, as this entails managing, testing, and developing practically separate products. Truthfully, not every business can really afford that, and few actually do it.

This turn of events has created a critical situation in the field of software development. The industry was in a dire need of an open platform that would allow them to build software at scale and meet all those platforms in a somewhat manageable way and within an affordable budget. At the time, the web showed great promise to fill in the gap. Nearly every device has a browser, and that was certainly a good starting point. Ever since, web development technologies and tooling have been evolving at a fast pace with great innovation, and the field keeps on gaining more popularity and demand.

Consequently, the web is one of the most versatile and dynamic fields today. Web developers have a tendency to be early adopters. Combine this with massive growth and you get exciting innovation. Additionally, the web community is keen on open source software, leading to great collaboration and contribution. Evidently, this is an exciting time to be a web developer. You have the ability to leverage the same skill set and become a true full-stack developer while enjoying cutting-edge innovation and massive collaboration.

Throughout this book, you learn how to build web apps using popular modern frameworks such as Angular, React, and Vue. Regardless of which framework you choose, when it comes to web apps, it still all boils down to the basic principles of the web: HTML, CSS, and JavaScript, as shown in the following diagram:

Next, let's cover these technologies, as these are the pillars of web apps, even though the expectation is that you are already familiar with, and have the experience to some extent with, these technologies.