Funds are a designation for how donation money will be spent in your organization. Most organizations have a general fund for unrestricted donations, as well as funds for specific purposes and projects. Fund is always a required field when you enter a gift.
If you plan to export your donations to your accounting software, the fund is where you associate a gift with the credit and debit accounts recognized by your accounting package. For each fund that you set up, you can associate only one bank account, one income or revenue account, and one receivables account. So if your accountant needs to allocate some donations to an unrestricted income account and others to a restricted income account, you must create two separate funds.
(Examples: General, Restricted, Scholarship)

Campaigns are an umbrella fundraising strategy with a specific focus that usually includes different approaches to solicit donations. They can have a defined start and end date, and usually have a monetary goal. Some organizations do not have many campaigns, and not all gifts have to be tied to a campaign. The Campaign field is not required when you add a gift, although your organization can choose to make it required.
(Examples: Annual Campaign, Capital Campaign)

Approaches are a solicitation strategy such as email, direct mail, event, or phone solicitation. Approaches track what method you used to collect each donation you receive. Keeping track of approaches can help you analyze how different types of asks perform with your constituents. The Approach field is not required when you add a gift, although your organization can choose to make it required. When you know what specific approach generated a gift, we recommend that you track it when you enter that gift.
(Examples: Direct Mailing codes, Phonathon, Events, Dinner Party)