Hi William!

I can see that @RCV has given a good start by sharing when to use categories or items. I'd be happy to provide you with a little more information.

You can use a category if you want to post directly to your categories, and if the items are too generic or too few to specify or don't have that high of an impact on your books. For example, instead of specifying a few items you bought like pencils, ball pens, etc., you can directly use the Office Supplies category. However, if you spend largely on them, you may want to itemize them instead.

The way you record your transactions will reflect on your financial reports and help you make wise business decisions. If you just use Office Supplies in your transactions, this won't give you a clue of which specific supply is costing you more money. Whereas, itemized transactions provide more information about the specific amount of money you spent on the items you bought. Things like these can help you decide to create actions to improve your finances.

On the other hand, we have references for QBO on the main support page should you need them in the future. Just scroll down a bit and click More topics.

Let me know if you have other questions about entering purchases or anything about QuickBooks. More power to your business!