When dining out what does tips stand for?

Tips are money that you leave for your server. Servers generally pay the IRS based upon (minimally) 8% of total sales. The average time a server spends serving someone is an hour. If you don't leave a tip for a server it will still cost them money out of their pay check to pay the IRS.

Answer'Tip' began as a verb in the seventeenth century, used in the language of thieves, meaning 'to give'. By the early eighteenth century, the meaning included "to give a gratuity to a servant or employee". The service person is not paid minimum wage, they are paid below that rate on the assumption that the public will augment their wage. It is to the server's advantage to give good service simply because the wise customer will generally tip 15% of the bill. In some establishments, this is also known as a "minimum" or "cover charge" to insure that the servers are treated fairly. 10% TIPS are generally left for so so service, 15% left for decent service and 20% or more is left for outstanding service.