Front-end development involves creating the user interface and user experience of a website or application. It includes languages and frameworks like HTML, CSS, JavaScript, React, and Angular. Back-end development involves server-side logic, database interactions, authentication, and API integrations. It includes languages and frameworks like Python, Node.js, Ruby on Rails, PHP, and databases like MySQL, MongoDB, and PostgreSQL.

Responsive web design is an approach to web design that ensures web pages render well on a variety of devices and window or screen sizes. This is achieved using flexible grids and layouts, media queries, and flexible images.

Common tools for front-end development include:

Code Editors:
VS Code, Sublime Text.

Browser Developer Tools:
For debugging and testing.

JavaScript Frameworks/Libraries:
React, Vue.js, Angular.

Version Control:
Git.