Different types of businesses will need different item classes for their inventory items. Your business may need more than one kind depending on what type of business you have.
Since you sell services, such as maintenance contracts, you will most likely want to set up:
In this type of business where you stock and sell inventory items, you are most likely going to want to set up:
In a manufacturing business that builds and sells products from raw materials, you will most likely want to use the following item classes:
A law firm or other professional organization that bills customers based on time and expense would most likely want to set up and use the following item classes: