The worldwide web is more than 30 years old, however, the internet is even older. But, in reality, the internet and the web is getting younger by the day as both computational power and networks get better and better.
In the early 2000s, the web was mostly made up of documents that contained only text and images. But, ever since then we have come a long way as you can see web applications nowadays are better at serving your needs very easily.
Web Browsers are great platforms upon which great products and services are built. They have become better and stronger over the years.
Let me give you an analogy to understand. Let's consider a car as our analogy.
This is the start of Web 2.0.
In the early 90's, the need was felt to add interactivity with the web page. Around same time, Java was popular and was coming up in big way. Java had became too big of a language to add interactivity to the web page and was an overkill for web designers and amateur developers.
There was a most popular web browser called Netscape Communicator. They were looking for a light-weight scripting language for the web which could be used for interactivity and manipulating contents of the web page dynamically.
Mocha made its debut in Netscape Communicator in the May of 1995. It was later named to LiveScript due to some marketing purposes.
Web Applications: Web applications are similar to websites, but instead, they get packaged into a neat little box, which improves control over security and more.
Browser Games: The modern web browser has come a long way; developers even make robust games that function in a browser.
Machine Learning: The libraries like ml5.js and tensorflow.js allows you to apply machine learning models in modern web development.