Add to Cart Button or link in Magento

<!--  Link -->

<a href="<?php echo Mage::helper('checkout/cart')->getAddUrl($_product); ?>"
data-toggle="tooltip"  title="Add to Cart">
Add to Cart
</a>

<!-- Button -->

 <button type="button" title="<?php echo $this->__('Add to Cart') ?>"
onclick="setLocation('<?php echo Mage::helper('checkout/cart')->getAddUrl($_product); ?>')"><span><?php echo $this->__('Add to Cart') ?></span></button>