HTML legend Tag

<form action="/actions/test.php">
    <fieldset>
      <legend>Login</legend>
      <p>
          <label>
              Username:
              <input type="text" name="username">
          </label>
      </p>
      <p>
          <label>
              Password:
              <input type="password" name="pass">
          </label>
      </p>
      <input type="submit" value="Login">
    </fieldset>
  </form>