Line screen (LPI)

Line screen, measured in lines per inch, is how fine the halftone dot pattern is on a printed piece.

Coated papers on offset commonly run around 150 lpi or finer. Uncoated paper and newsprint use coarser screens because the ink spreads into the fibers. You normally do not set this; the printer does.

Not sure what your job needs? Ask the people who print it.