Instruct: Classify a review as either positive or negative.
Query: Great for USA

If you are tipping in USA or Canada, this is a good guide. It gives you the history of guiding as well as what's expected by whom and why. It's also good for learning how to report tips as part of your salary. It is not good for traveling overseas. There is no advice on what's appropriate in the 21st century as you travel abroad.