         <div class="panel panel-default">
           <div class="panel-heading">Search</div>
           <div class="panel-body">
             <form>
               <div class="input-group">
                  <input type="text" class="form-control" placeholder="search ...">
                  <span class="input-group-btn">
                    <button class="btn btn-warning" type="button"><span class="glyphicon glyphicon-search"></span>          
                    </button>
                  </span>
               </div>  
             </form>
           </div>
         </div>  <!-- end search panel -->       
      
         <div class="panel panel-info">
           <div class="panel-heading">Continents</div>
           <ul class="list-group">               
              <li class="list-group-item"><a href="#">Asia</a></li>
              <li class="list-group-item"><a href="#">Africa</a></li>
              <li class="list-group-item"><a href="#">Europe</a></li>
              <li class="list-group-item"><a href="#">North America</a></li>
              <li class="list-group-item"><a href="#">South America</a></li>    
           </ul>
         </div>  <!-- end continents panel -->  
         <div class="panel panel-info">
           <div class="panel-heading">Popular Countries</div>
           <ul class="list-group">               
              <li class="list-group-item"><a href="#">Bahamas</a></li>
              <li class="list-group-item active">Canada</li>
              <li class="list-group-item"><a href="#">Germany</a></li>
              <li class="list-group-item"><a href="#">Ghana</a></li>
              <li class="list-group-item"><a href="#">Greece</a></li>
              <li class="list-group-item"><a href="#">Hungary</a></li>
              <li class="list-group-item"><a href="#">Italy</a></li>
              <li class="list-group-item"><a href="#">Spain</a></li>
              <li class="list-group-item"><a href="#">United Kingdom</a></li>
              <li class="list-group-item"><a href="#">United States</a></li>    
           </ul>
         </div>  <!-- end countries panel -->    