Third-party payment providers
If you're not using Shopify Payments and you want to accept credit cards, then you can choose from over 100 credit card payment providers for your Shopify store.
Shopify supports two different types of credit card payment providers: direct providers and external providers. If you're using a direct provider, then your customers can complete their purchases directly on your online store without having to pay at a third-party checkout. If you're using an external provider, then your customers must complete their purchases on a checkout page that's hosted outside of your online store.
You can activate or change a payment provider from the Payments page of your Shopify admin.