What is a 'query parameter' used for in web development?

A query parameter in web development refers to a key-value pair included in a URL, primarily used to modify the request sent to the server. When a web page is requested, query parameters can provide additional information to the server about what data the client is looking for. For instance, if a user wants to filter a list of products by category on an e-commerce site, the URL might look something like this: https://example.com/products?category=shoes. Here, category is the key, and shoes is the value.

This mechanism allows developers to easily retrieve specific data based on user input or other criteria, enabling functions such as sorting and filtering. When the server processes the request, it uses the parameters in the query to determine which data to return to the client, making it a powerful tool for web applications.

In contrast, other options describe different functionalities that do not involve query parameters. Secure connections, user authentication, and dynamic content updates are all important components of web development but operate through different mechanisms than those provided by query parameters.