The label 1) html element represents a caption for a control item in a form (user interface).
<label for="username">The name of the user: </label>
<input type="text" id="username">
<label>The name of the user: <input type="text"></label>
A click on the label:
Demo for the focus
<label for="username">Click me to focus on the input: </label>
<input type="text" id="username">
Demo for the propagation. When you click on the label, the checkbox is checked/unchecked
<label for="checkbox">Click on me to check/uncheck the checkbox</label>
<input id="checkbox" type="checkbox" />