Direct answer: Birch tar is a sticky material made by heating birch bark in low-oxygen conditions. It is famous in archaeology as one of the oldest known human-made adhesives.
Birch bark contains compounds that can be transformed into a dark adhesive when heated carefully. Archaeological finds show that birch tar was used long before modern glues, including for hafting stone tools and repairing or sealing objects. It is especially important because it appears in debates about Neanderthal technology and early human craft skill.
The classic use of birch tar is adhesive work: binding a stone blade to a handle, sealing joins, repairing ceramics, or attaching small components. It was also chewed in some ancient contexts, which has allowed researchers to recover human DNA from pieces with tooth marks. It is mainly as an archaeological and craft material rather than a household glue.
Birch tar differs from pine tar in both source and behaviour. Pine tar is usually discussed as a wood and rope preservative. Birch tar is most famous as a compact adhesive or pitch-like mass. It may be called birch bark tar or birch pitch in archaeological writing.
In short: Made from birch bark rather than pine wood. Known from Middle Palaeolithic archaeological contexts. Used as an adhesive, sealant, and repair material. Often called birch bark tar or birch pitch.