“Apple Tree” is the name of the block representing the trunk of apple trees. They can be found in deciduous forests (→Biomes) and appear either as part of a full-grown tree or apple tree together with Leaves and sometimes Apples or as a “fallen log“, sometimes with a Brown Mushroom on it.
These blocks can be crafted by the player into Apple Wood Planks and used in a furnace as a fuel for smelting. You can mine them with an axe efficiently, but mining by hand is also possible.
The apple tree block is grown from apple tree saplings.
As a Crafting Ingredient