Web development involves both front-end development and back-end development. Front-end development includes using languages like HTML, CSS, and Bootstrap to define the layout and visual design of websites. Back-end development involves using languages like SQL and PHP to manage the database and functional aspects of websites that users do not see. Key front-end technologies are HTML for content, CSS for styling, and Bootstrap for responsive design. Key back-end technologies are SQL for databases and PHP for server-side scripting.