The Classes App allows you to create unique classes to assign to transactions, making it easy to categorize and report on different aspects of your business. Classes can be created and edited in Method without having to switch to QuickBooks, because the classes you create and update are saved to QuickBooks during your next sync.
A class is a way of categorizing income and expenses in QuickBooks. The way classes are assigned to transactions depends on your business, but in all cases, they are used to filter and organize transactions to make it easier to keep track of your money.
For example, a landscaping company might want to track the profitability of different types of jobs: maintenance, installation, and so on. Assigning those classes to transactions makes it easy for your accountant to generate reports based on those criteria.