Angular is a popular open-source web application framework developed and maintained by Google. It is used for building dynamic and efficient single-page web applications (SPAs) and progressive web apps (PWAs). Angular is written in TypeScript and follows the Model-View-Controller (MVC) architectural pattern.

Key features of Angular include:

1. Declarative Templates: Angular uses HTML templates enhanced with additional syntax to define the UI and data bindings. This allows developers to declaratively describe the application’s user interface and its behavior.
2. Component-Based Architecture: Angular applications are built using components, which are self-contained, reusable building blocks that encapsulate the HTML, CSS, and behavior of a part of the UI.
3. Dependency Injection: Angular has a powerful dependency injection system that allows components and services to request their dependencies instead of creating them directly. This promotes modularity, testability, and maintainability.
4. RxJS: Angular leverages Reactive Extensions for JavaScript (RxJS), a library for handling asynchronous operations and event handling with observable streams. RxJS is extensively used for managing data flow in Angular applications.
5. Routing: Angular provides a robust routing mechanism to enable navigation between different views or pages within the application without requiring a page reload.
6. Forms: Angular offers powerful form handling capabilities, including form validation and form control binding.
7. Directives: Angular has custom HTML attributes known as directives, which allow developers to extend the behavior of existing DOM elements or create reusable custom elements.
8. Services: Services in Angular are used to encapsulate business logic, data retrieval, and other operations that can be shared across components.
9. HTTP Client: Angular provides an HTTP client module to interact with RESTful APIs and perform HTTP requests.
10. Internationalization (i18n) and Localization (l10n): Angular supports multi-language applications through its built-in i18n and l10n features.

It’s important to note that Angular should not be confused with AngularJS. AngularJS (version 1.x) was the first version of the framework, but Angular (also known as Angular 2+ or simply Angular) is a complete rewrite of the original framework with significant improvements in performance, modularity, and other areas.

To develop Angular applications, developers typically use the Angular CLI (Command Line Interface), a command-line tool that assists in creating, building, testing, and deploying Angular projects.

Angular has a large and active community, extensive documentation, and a wide range of third-party libraries and plugins available, making it a popular choice for building modern web applications.