Generalisation is a foundational element of logic and human reasoning. It is the essential basis of all valid deductive inference. The concept of generalisation has broad application in many related disciplines, sometimes having a specialised context-specific meaning.

For any two related concepts, A and B; A is considered a generalisation of concept B if and only if: every instance of concept B is also an instance of concept A; and there are instances of concept A which are not instances of concept B. For instance, animal is a generalisation of bird because every bird is an animal, and there are animals which are not birds (dogs, for instance)