wha are tags used for ?

You can use the Search bar at the top of any page to find answers to most questions.  

In doing so, I was able to find something from Intuit/ QB that may answer your question. 

https://quickbooks.intuit.com/learn-support/en-us/help-article/accounting-bookkeeping/tags-use/L2JPGqChX_US_en_US#M8699

We value your participation in the Community, @seperdue. Organizing your transactions is essential for tracking your business effectively, and using labels or tags is a great way to simplify this process.

In QuickBooks Online (QBO), tags function similarly to labels and are essential since they make it easier for you to keep track of all your transactions. They allow for more detailed oversight of business activities, which can be especially helpful for businesses with diverse operations or multiple income streams. Furthermore, you are free to modify the transaction's label whenever you see fit.

For reference and more details regarding tags in QuickBooks Online, you can read the following articles:

• What are tags and why should I use them?
• How to tag any transactions in QuickBooks Online
   

If you like to track your transactions by class in QBO moving forward, you can have this link as your guide on doing so.

Whenever you require additional assistance regarding how tags work in QBO or any QuickBooks-related matters, please feel free to go back to this thread. Have a wonderful day!