A Donorfy Transaction has 3 essential codes. They are:
A Campaign is the thing that prompts someone to make a donation. It could be a mailing, an event, an online giving page etc. It is so you can track the effectiveness of each fundraising activity you do. A Campaign exists on the Payment part of a Transaction.
A Product is what the donor is paying for when they make their contribution. Normally it would be a Donation, but could also be a Subscription (e.g. if you have a membership scheme), a Raffle ticket, a Book. You can manage the list of Products in the Settings area. You can set the eligibility for Gift Aid at Product level. A Product exists on the Allocation part of a Transaction.
A Fund is the destination for the money - the 'pot'. For example you may have a range of reserved funds and a general. A Fund exists on the Allocation part of a Transaction.
You can set defaults for all three - see Transaction Entry Defaults in Settings.