Some patterns don't include an edge stitch in the count, but they usually tell you to add a stitch at each end for an 'edge stitch' or selvedge stitch.
Most patterns will include it and then say something like "working edge stitches in stockinette, repeat patterns rows for umpty-dump times." It just means to keep the two edge stitches in stockinette.
Sometimes you slip the first stitch of each row for a smoother edge, or work it in garter.
It really depends on the pattern, and whether it's seamed or not.