I was expecting an article about DPI (as in raster printing dots), but it ended up being about PPI (as in screen pixels). DPI in print is something I see many

I was expecting an article about DPI (as in raster printing dots), but it ended up being about PPI (as in screen pixels). DPI in print is something I see many get wrong, and most don't understand the difference between DPI, LPI and PPI.