An expense type account is used to allow you to track how much you spend on specific expenses. Many people's first experience with tracking expenses comes from Quicken(tm), where transactions can be assigned to one or more categories. In GnuCash, these categories are set up as separate accounts, which are designated as Expense type accounts. This allows GnuCash to apply the rules of double-entry accounting consistently. Expense accounts can be as detailed or as general as you need. Some users need only a few accounts for personal expense tracking. Others use GnuCash expense accounts to manage their expenses in great detail. The level of detail you choose is up to you. Keep in mind that with GnuCash, you can change accounts for transactions, so if your needs change later on, it is possible to move transactions around.