Make sure you’re calling bootstrap.min.js
after jquery.min.js
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel=stylesheet href=https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css>
<a href="#" data-toggle="modal" data-target="#modalTC">terms and conditions</a>
<!-- Modal -->
<div class="modal fade" id="modalTC" role="dialog">
<div class="modal-dialog">
<!-- Modal content-->
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">× </button>
<h4 class="modal-title">Modal Header</h4>
</div>
<div class="modal-body">
<p>Some text in the modal.</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
</div>
</div>
</div>
</div>