URL parameters, also known as query parameters or query strings, are key-value pairs appended to the end of a URL. They are separated from the base URL by a question mark "?" and from each other by an ampersand "&". URL parameters are used to pass information to the server about the request or to modify the behavior of the requested resource. Each parameter consists of a key and a corresponding value.

Here's an example of a URL with parameters:

https://www.example.com/page?name=John&age=25&city=NewYork

In this example, name, age, and city are the parameters, and John, 25, and NewYork are their respective values. The URL parameters can be used for various purposes, such as searching, filtering, sorting, or customizing the content displayed on a web page.

Web applications often use URL parameters to pass data between different pages, customize user experiences, and enable features like search functionality. The server processing the request can access these parameters and use them to generate a specific response based on the provided values.