Mode

A payment transaction can be in two different mode :

If you've setup your Product in Payment mode : test, a person buying the product can use Stripe test card :

Card number : 4242424242424242
CVC : Any 3 numbers
Date : Any date in the future the payment will then be created in test mode and nothing will be charged. This is useful when testing your integration.

If you've set up your product as live, real payments will happen.