This is a sort of all-in-one solution that encompasses all of your web hosting and ecommerce functionality. You'll pay a monthly or yearly fee which will include your web hosting, ecommerce system, payment processing and support.

Pros - It's all done for you, ready to go. Good services like BigCommerce (my favorite) and Shopify make it really easy to get your ecommerce site set up, designed and operational.

Cons - Typically, higher monthly costs. Adding additional, non-ecommerce functionality to your site (like a WordPress blog) may not be possible. Customization and design options are limited, albeit pretty darn acceptable in most cases.