React is a popular JavaScript library developed by Facebook for building user interfaces, particularly for single-page applications. Its declarative approach allows developers to create dynamic and responsive web applications with ease. One of the core concepts of React is the component-based architecture, which promotes reusability and maintainability of code. A React component is essentially a JavaScript function or class that takes input, known as props, and returns a React element that describes how a section of the UI should appear. This modularity not only enhances productivity but also simplifies debugging and testing processes.

To get started with React, it's crucial to understand some basic terminology. A component can be either stateful or stateless. Stateful components manage their own data and can respond to user inputs, while stateless components are purely presentational and receive data via props. Another important concept is the Virtual DOM, which optimizes the rendering process by minimizing direct manipulations of the actual DOM, resulting in improved performance. As you dive deeper into React, you'll encounter tools like React Router for navigation and Redux for state management, aiding you in building robust applications.

When it comes to efficient React development, following best practices can significantly enhance both performance and maintainability of your applications. Here are the top 10 best practices that every React developer should adopt:

1. Component Reusability: Create reusable components that can be utilized throughout your application to reduce redundancy and increase consistency.
2. State Management: Leverage state management libraries like Redux or Context API to ensure that your application's state is predictable and easier to manage.
3. Code Splitting: Implement dynamic imports to split your code into smaller bundles, which helps to improve load times and performance.
4. Use React Developer Tools: Utilize browser extensions like React Developer Tools to debug your applications more effectively.
5. Prop Types Validation: Enforce your component’s expected props using PropTypes, which helps in catching bugs early during development.

Continuing with the best practices for efficient React development, consider the following:

6. Performance Optimization: Utilize memoization with React.memo and useMemo to prevent unnecessary re-renders that can slow down your application.
7. Keep Components Small: Break down large components into smaller, more manageable ones, which enhances readability and simplifies testing.
8. Optimize Render Methods: Avoid inline functions in render methods, as they can create new instances on every render, negatively impacting performance.
9. Consistent Styling: Use CSS Modules or styled-components to keep your styles organized and scoped to your components.
10. Testing: Implement unit and integration testing to ensure that components work as expected and to catch potential issues early in the development process.

Building a responsive web application using React components involves several key steps that ensure your application is both visually appealing and functional across different devices. To start, you must create a project using create-react-app, which sets up a modern web development environment. Next, break down your UI into reusable React components. This modular approach not only enhances maintainability but also improves the responsiveness of your application. Ensure that each component is designed with flexibility in mind, allowing them to adapt to varying screen sizes by utilizing CSS frameworks like Bootstrap or utility-first libraries such as Tailwind CSS.

Once you have your components structured, focus on implementing responsive design principles. Use CSS media queries to adjust styles based on the viewport size. For example, you can change font-size, padding, or flex-direction based on the screen width. Additionally, consider incorporating React hooks like useWindowDimensions to dynamically adjust components based on the current screen size. This approach allows your application to provide an optimal viewing experience for users on both mobile devices and desktops, thereby enhancing user engagement and satisfaction.