Ember.js

Ember.js is a JavaScript framework used for developing web applications. It provides a complete solution for building client-side JavaScript applications and is known for its convention over configuration and the "don't repeat yourself" principles.

Ember.js follows the MVVM pattern, which facilitates the separation of concerns by dividing the application into models (data), views (presentation), and view models (logic that ties the two together). Ember.js emphasizes convention over configuration, meaning it provides standard ways to structure your application and expects certain patterns to be followed. This approach helps in reducing the amount of boilerplate code and decisions developers have to make.

Ember.js includes a powerful routing system that makes it easy to manage URL state in your application. This is central to Ember’s philosophy and is one of its standout features compared to other frameworks.

The framework encourages the use of components - reusable, encapsulated elements that can manage their own layout and behavior. These are akin to custom, reusable HTML tags. Ember.js uses Handlebars, a simple templating language, to control how the view layer is rendered. Handlebars templates look like regular HTML, but also contain expressions that change the rendering based on the underlying data.

Ember Data is a library that provides a consistent way of interacting with external APIs and managing application data. Ember.js has a strong community and ecosystem, offering a range of addons and extensions that can be easily integrated into Ember applications.

Ember.js is particularly well-suited for ambitious web applications where there is a need for a rich single-page application (SPA) experience. It's used by many large-scale websites and applications due to its robustness and comprehensive feature set.