Frontend development is the practice of building the user-facing part of web applications that users interact with directly in their web browsers. It encompasses:

1. Markup and Structure: Using HTML (Hypertext Markup Language) to create the foundational structure of web pages, defining elements like headings, paragraphs, images, and links.

2. Styling: Applying CSS (Cascading Style Sheets) to enhance the visual design and layout of web pages, allowing for control over colors, fonts, spacing, and overall aesthetics.

3. Interactivity: Implementing JavaScript to create dynamic features and interactive elements, such as forms, animations, and real-time updates, enriching user engagement.

4. Frameworks and Libraries: Leveraging modern frameworks (like React, Angular, and Vue.js) and libraries (like jQuery) to streamline development, improve maintainability, and build complex user interfaces efficiently.

5. Responsive Design: Ensuring that web applications are accessible and visually appealing across various devices and screen sizes by using techniques like fluid grids and media queries.

6. Performance Optimization: Enhancing the speed and efficiency of web applications through practices like minimizing file sizes, optimizing images, and implementing lazy loading to improve user experience.

7. Cross-Browser Compatibility: Testing and ensuring that applications function correctly and consistently across different web browsers and devices.

8. Version Control: Using systems like Git for tracking changes in code and facilitating collaboration among developers.

9. User Experience (UX) and User Interface (UI) Design: Collaborating with designers to implement user-friendly interfaces and improve overall user experience through thoughtful design choices.