Pine is an inexpensive, lightweight wood that can be yellowish or whitish with brown knots. It's often used for rustic pieces, like farmhouse-style tables.
Pros: It's low-cost, and it takes paint well, so it's great for kids' furniture. (The same holds true for birch and poplar.) Pine develops a nice, rustic patina from age and use, and it resists shrinking and swelling.
Cons: It's a softwood, so it's prone to scratches and dents.