Getting user input using HTTP GET

HTTP GET requests are the simplest way of retrieving input from the user. You might have noticed question marks in URLs while browsing the Web. When submitting a term in the search box on the website, your search term will usually appear in the URL, and look something like this:

example.com/search?query=weather

The bit after the question mark represents a named GET argument. The name is query and the value, weather. Although arguments like these are usually automatically created through HTML input boxes, the user can also manually insert them into the URL, or they can be part of a clickable link that is sent to the user. HTTP GET is designed to get limited, non-sensitive information from the user in order for the server to return a page as requested by the GET arguments. By convention, GET requests should never modify the server state in a way that produces side effects, that is, the user should be able to make exactly the same request multiple times and...