Hickory bats were the most common type of bats used in baseball's infancy. Hickory is a strong wood that doesn't easily break, but because of the heavy weight, hickory fell out of popularity with baseball players when lighter bats came into existence. However, the Coach John Peter's Baseball Tips website states that, with modern drying techniques (which remove moisture and ultimately weight from the bat), hickory bats may soon make a comeback in the major leagues.
Most baseball bats are made out of white ash grown in the northeast United States. Ash has the sought-after characteristics of light weight, great durability and exceptional hardness. Only the best white ash is used to make major-league quality baseball bats. However, lower quality ash bats exist and are sold cheaply at most sporting good stores.
Maple bats became popular in the 1990s and the 2000s after the technology was developed to lower the weight of the bat by removing moisture. Bats made out of quality maple (rock or sugar maple) are excellent tools, but bats made out of cheaper maple do not hold up as well. Maple bats, even low quality ones, will cost more than ash bats.
Bats made out of bamboo are very strong (bamboo actually has a greater tensile strength than steel), and because of this, some baseball players prefer using bamboo baseball bats. Because of the special qualities of bamboo, the actual production of bamboo bats differs from that of other wooden bats.
Composite wood bats are made out of a mixture of different woods and wood blends. Like bamboo bats, composite bats are made by combining inner supports and several smaller wood billets to create one bat. The obvious difference is that bamboo bats are made out of a single type of wood while composite bats can be made of several combinations of wood. Composite bats tend to be significantly more durable than regular wooden bats. Composite bats are usually more expensive than other types of wood bats.