React is currently the most popular JavaScript framework. It was developed by Facebook, and is used to create user interfaces. It utilizes a Virtual DOM, which is faster and more lightweight than the actual DOM. It also uses a markup language called XML - which is very similar to HTML - with a few minor changes. React is supposedly "easier to learn" than some other frameworks, which adds to its popularity.
Angular is an open-source framework that is primarily used to create Single Page Applications. It is built on TypeScript, and utilizes components, similarly to how React handles them. It is more complex, with a steeper learning curve than some other frameworks, which is perhaps why it is more commonly used by larger companies.
Vue is similar to React in that it uses a Virtual DOM and builds user interfaces. Vue updates the DOM by listening to changes within a component's state. Vue is known for its fast performance and overall efficiency, but typically is not preferred for large-scale projects.
JavaScript frameworks improve the overall development process and can provide features that may not be available with vanilla JavaScript. Each framework has different strengths and weaknesses, so different companies and developers may prefer one framework over another.