Angular is an open-source web application framework developed and maintained by Google and a community of developers. It's used for building dynamic, single-page applications (SPAs) and web applications with rich user interfaces. Angular provides a comprehensive set of tools and features to help developers create complex and scalable applications.

Key features and concepts of Angular include:

1. Component-Based Architecture: Angular applications are built using components, which are reusable and encapsulated building blocks for UI elements. Components are organized in a hierarchical structure and communicate with each other using inputs, outputs, and services.

2. Dependency Injection: Angular has a built-in dependency injection system that manages the creation and sharing of application components and services. This promotes modularity and testability by making components more independent and easier to test.

3. Templates and Directives: Angular templates use a declarative syntax to define the structure and behavior of the UI. Directives, such as `ngFor` and `ngIf`, allow you to manipulate the DOM, apply conditional rendering, and iterate over data.

4. Reactive Programming: Angular leverages reactive programming concepts with the RxJS library. Observables are used to handle asynchronous data streams and facilitate real-time updates in the application.

5. Services: Services in Angular are used to encapsulate business logic, data manipulation, and interaction with external resources (like APIs). Services are injectable and can be shared among components.

6. Routing: Angular provides a powerful routing system that allows you to create multi-view applications with client-side routing. You can define routes, navigate between views, and load components dynamically.

7. Forms: Angular offers a robust form handling system that supports both template-driven forms and reactive forms. It helps manage form state, validation, and user input.

8. Modules: Angular applications are organized into modules, which provide a way to group related components, services, and other features. Modules help with modularity, code organization, and lazy loading.

9. Angular CLI: The Angular Command Line Interface (CLI) is a tool that simplifies the creation, development, and deployment of Angular applications. It provides commands for generating components, services, modules, and more.

Angular is suitable for a wide range of projects, from small applications to large enterprise-level applications. It's known for its strong typing, strict coding practices, and extensive tooling ecosystem. Although it can have a steeper learning curve compared to some other frameworks, it offers a comprehensive solution for building robust and maintainable web applications.