For Freud, the fundamental constructs of Human Personality, are as follows:
D.1. Id: From German Das Es, The It, pre-existing at the time of birth, a cauldron of seething excitations, the Id transforms our physiological needs into psychological tensions, or derives, aims at gaining pleasure by derive reduction, and remains indifferent and precedent to all morality and rationality, reality and self preservation, and thereby initiates the Primary Process of mind.
D.2. Primary Process: The natural process of mind pre-existing all rationality, and morality where opposites and conflicting views co-exist, and all related concepts are condensed into single entity. Everything here is indifferent to time, and impervious to experiences.
D.3. Ego: From German Das Ich, The I, born out of the Id at around age of 06 months, is consequence of and is nourished by our experiences of things in our environment which are of a service, or a disservice to the demands of the Id, and is in essence our preference for self preservation. It triggers the Secondary Process.
D.4. Secondary Process: It is the rational process aimed at preserving the self while being at the service of Id, and thus it focuses on problem solving and pleasure delaying for a more secure, or more enhanced experience of pleasure.
D.5. Subjectivity of the Ego: Unlike Id, the Ego is the child of Id, and at once subject to the experiences of the real world. Thus, it is subject to both masters – the realities of environment of man, and the derives from Id – and accordingly, it may, from time to time, serve one master more than the other, depending upon the strength of the derive of the Id, and the conditions of the environment it has experienced.
(Incomplete - to be updated later)
Reference: Ewen, R. B. (2014). An introduction to theories of personality. Psychology Press.