What is the difference between an lpi dpi ppi?

LPI - Lines Per Inch - Refers to the number of lines of text a printer will fit in an inch of paper. (the smaller the font size the more lines per inch)

DPI - Dots Per Inch - The number of dots a printer can put within an inch of paper (the smaller the print nozzles the more DPI'

PPI - Pixels Per Inch - usually relates to the resolution of a monitor.