Case is $$Travel Itinerary Planner$$ for this case build a web app for users to plan and book entire trips, including flights, hotels, and activities.

Development Steps:

$$ User Interaction and Database Design: Develop a database system to manage user profiles, authentication, and page customisation. Utilise an SQL database and PHP to establish connectivity between the website and the database.

$$ Design Layout and User Interface: Create the web application's layout and user interface using HTML and CSS$.$ This encompasses defining the overall structure of the web application and styling various page elements.

$$ Logic and Functionality Implementation: Implement the web application's logic and functionality using JavaScript and PHP$.$ This might include tasks like form validation, database integration, and server$-$side processing.

$$ Testing and Validation: Thoroughly test the web application to ensure functionality and user$-$friendliness. Conduct both manual and automated testing if necessary.