How can you prevent a form field value from being edited by users in PHP?

To prevent a form field value from being edited by users in PHP, you can use the "readonly" attribute in the HTML input field. This attribute makes the input field read-only, meaning users can see the value but cannot edit it. This is useful for displaying information that should not be changed by the user.

<input type="text" name="username" value="JohnDoe" readonly>