title_body: Does the coarseness of the ground coffee affect taste
upvoted_answer: Required reading for any aspiring home barista: https://www.home-barista.com/tips/espresso-101-how-to-adjust-dose-and-grind-setting-by-taste-t16968.html
  
  Basically, coarseness of the grind influences the balance of bright and bitter flavors: coarser reduces bitter flavours, finer reduces acidic flavours. But it all interacts with the flow rate; see the diagrams in the linked article.
  
  
  
  Tamping pressure itself is not really a factor, you should keep this constant and only modify grind and dose.