OPTGROUP
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<!DOCTYPE html>
<html>
<body>
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<h1>The optgroup tag</h1>
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<p>The optgroup tag is used to group related options in a drop-down list:</p>
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<label for="Programming Languages">Choose a Programming Language:</label>
<select id="Programming Languages">
  <optgroup label="Front-End">
    <option value="HTML">HTML</option>
    <option value="CSS">CSS</option>
  </optgroup>
  <optgroup label="Back-End">
    <option value="Java">Java</option>
    <option value=".Net">.Net</option>
  </optgroup>
</select>
 
</body>
</html>