transcendental subject

Synthetic unit of consciousness:
Kant describes it as the unity that integrates all representations and makes them possible.
Pure apperception:
It is the self-awareness that precedes all experience, a pure awareness of one's own identity.
A priori conditions of experience:
It is the subject that provides the fundamental forms of experience, such as space and time, which make understanding the world possible.

The transcendental subject, in philosophy, refers to an abstract mental entity considered the necessary condition for experience and knowledge to be possible. It is the point of reference from which experience is constructed and is distinguished from the empirical subject, which is the individual person with their particular characteristics.