The first baby poop
Technically called meconium, this is the dark greenish black sticky stuff that you'll first see in diapers. It's not true poop but basically an elimination of a substance found in your baby's intestines while he's womb-bound.
Real newborn poop
This is a yellow, mustard, brownish poop that occurs early on. Usually this is less smelly than what's to come later. You may see small seed-like bits in this poop; no worries, that's normal.
Yuck, right? Once your babe starts on solids, his poop is going to get icky and smell way worse. Your baby's poop may be green, orange, or another food-like color, which is normal.
Babies who are fed formula have different poop than breastfed babies (commonly that mustard-looking stuff mentioned above). If your baby eats formula, his poop may be darker brown and can smell of iron vitamins. This is typical and nothing to worry about.