html input readonly

HTML
<!--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">
</form><!-- Using readonly attribute is use to prevent changing of input value. -->
Example:
<input type="text" name="username" value="ankur" readonly>
Source

Also in HTML: