Logs are the base form of wood in the Lumber Tycoon 2. Upon chopping a tree, you will be able to carry the log around, just like any loose object (usually to a Sawmill or the Wood Dropoff at the Wood R Us). After putting the log into a sawmill, the value increases by a certain multiplier depending on the Sawmill used, and then becomes planks. Unlike planks, logs do not save on your base and leave the logs on the spot when you leave. And they will stay there until it despawns or is claimed by a player.
Logs have an outer bark layer and the core. The core is usually lighter colored than the bark (but there have been exceptions, like walnut wood), and the core is always the color of its planks. Logs can be very long, and hard to fit in the sawmill. A log has to be under 10 units in length, with the exception of the Sawmax 02L which can mill logs with 16 units in length, or else it will not be able to fit into any sawmill. The width of a log that can fit in a sawmill depends on the type of sawmill, with the Sawmax 02 being able to fit almost everything if placed correctly. Even though the Sawmax 02 and 02L both have the largest input hole currently in the game, some wood types, such as Lava, Walnut, Koa, Phantom, Cavecrawler, and the infamous Spook and Sinister Wood have problems with fitting into the sawmill, usually requiring the player to angle - force the wood or do the Move + back glitch. This is usually the case for the trunks of each of these trees. So far, Phantom trees, Snowglow trees and Palm trees are the only trees that have a different log texture than its plank.