Check out example codes for "read only attribute in html". It will help you in understanding the concepts better.

Code Example 1

<!-- Using readonly attribute is use to prevent changing of input value. -->
<input type="text" name="username" value="ankur" readonly>

Code Example 2

<!--The readonly attribute means that the value of an input element
cannot be changed-->
<form action="/action_page.php">
<label for="country">Country:</label> 
<input type="text" id="country" name="country" value="Norway" readonly><br><br>
<input type="submit" value="Submit">

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