Web development is the process of building websites and web applications. It involves creating both the structure and appearance of a website, as well as implementing functionality such as forms, navigation, and interactive elements. HTML, or Hypertext Markup Language, is the basic building block of web pages. CSS, or Cascading Style Sheets, is used to control the presentation and layout of HTML documents. Together, HTML and CSS form the foundation of web development, enabling developers to create websites and web applications that are both functional and visually appealing. They are essential tools for anyone looking to build a presence on the internet.