There are some terms we use throughout the Chippin document that may be unique to the domain or our service. These are:

Callback: At certain points throughout a 'chippin' your site will receive 'callbacks' to indicate the state of the purchase. Some of these callbacks occur without the instigator or contributors knowing, others are simple redirects at the end of a process for a given user type. We detail these in the Callbacks section.

'chippin' (as in,a 'chippin'): the process in which a customer attempts to reach a monetary target within a specified time to complete a transaction with a merchant (e.g. to raise £250 for a gift in three days between three friends). The customer will always invite at least one other person to contribute, but can successfully complete a purchase even if no-one else chips in.

Contributor: This is someone the instigator has invited. A person that they want to contribute to the group purchase.

Grace period: This is the time allowed by the merchant for the instigator to pay any outstanding balance once the time limit for all contributors to chip in has elapsed. This allows the instigator to complete the purchase by paying and then chasing up any other contributions in a traditional manner.

Instigator: This is the customer of the merchant. The person wishing to purchase something and going through the merchant's checkout process online.

Merchant: You, the store owner. The Chippin account holder.

Pre-authorisation (and Authorisation): when a customer's payment card is 'pre-authorised', the card processor (in our case, Stripe) verifies that the customer's account is valid and that sufficient funds are available to cover the transaction's cost. At this step, the funds are "held" and deducted from the customer's credit limit (or available bank balance, in the case of a debit card) but are not yet transferred to the merchant. The amount is not charged (or authorised) until the 'chippin' is successful. If the 'chippin' fails, the hold is removed and the funds are released back to the customer's account.