For today’s busy parents, anything that can make life with a little one simpler is ideal. That is why many parents are choosing the Pack n Play. However, with the Pack n Play, you may also want a good pack n play mattress pad that is going to add extra comfort. It goes without saying that an uncomfortable baby is less likely to nap as planned.

The English language has several terms for children between the ages of birth and 4 years, including newborn, infant, baby and toddler. Here's a look at each of these terms, what age range they apply to, and an overview of the growth and development you can expect during that time.