How do you retrieve a value from the $_POST array?

Retrieving a value from the $_POST array is achieved by using the key associated with the posted value. The $_POST superglobal array is an associative array that holds data submitted through HTTP POST requests. Each key in this array corresponds to the name attribute of an HTML form element that was submitted.

For example, if you have a form input like <input type="text" name="username">, after form submission, you would use $_POST['username'] to access the entered value for that key. This direct association of keys with values allows for straightforward retrieval of submitted data.

While other options mention methods or functions that do not exist in the context of PHP's $_POST, the correct approach is to simply refer to the key of the form element as described. This foundational knowledge is crucial for handling form submissions effectively in PHP applications.