In Next.js, dynamic routes are defined by placing the parameter inside square brackets ([]) in the page file name. For example, if you have a dynamic route for displaying a user's profile, you can create a file called [username].js. The username inside the brackets is the parameter that will be used to generate dynamic pages.
To handle dynamic routes, Next.js provides a special component called getServerSideProps or getStaticProps. These functions allow you to fetch data based on the dynamic parameter and pass it as props to the page component.
