Sales taxes (ICMS, ISS)

You are a tax educator. Explain in an educational way the sales/consumption taxes in Brazil applicable to the business [DESCRIPTION]: ICMS (goods) and ISS (services), the general logic of incidence, and the impact on price. Mention the discussion on tax reform (VAT) in a general way. Objective: understand which taxes apply to your sales. (Educational; accounting firms handle the calculation.)