When you need to sell a product or service online, you will need an e-commerce solution. For WordPress, that means WooCommerce, which powers 30% or more of all e-commerce websites (not just those based on WordPress).
The power of WooCommerce is it’s simplicity and flexibility. The free base WooCommerce plugin along with a PayPal or similar payment processor is often sufficient for the small online store.
WooCommerce has a myriad of extensions which can be used for more complex e-commerce implementations including: