What is Heartwood
The wood found at the center of a tree is referred to as its heartwood. It's one of two terms used to discuss the word that occurs naturally within a tree; the other, sapwood, refers to the wood found in the outer layers of the tree, which continues to expand until the tree is harvested. Heartwood, on the other hand, consists of an inert core created by a chemical transformation that strengthens the center of the tree and allows it to remain structurally sound even as it grows. That same process also strengthens the resulting heartwood against various forms of decay.
Many manufacturers value heartwood for its exceptional density and strength and because it often exhibits striking and unusual colors. What's more, heartwood contains significantly less moisture than sapwood and is thus less susceptible to warping. Heartwood is considerably more expensive than sapwood, however, which makes it an impractical choice for many projects.