Introduction to Abhidhamma

Introduction to Abhidhamma
Abhidhamma is colossal and any attempt at simplifying it is difficult, simply because of the fact that Abhidhamma in Buddhist terminology is an attempt to finely describe the working of the Mind.
It is a conceptual framework  of “phenomena of existence” of physical and mental formations; i.e; analysis of mental phenomena and their conditioning.
This analysis is the basis for expounding the very nature of existence of the being (Bhava) conditioned by Anitta (impermanence), Dukka (unsatisfactoriness based on impermanence) and hence Anatma (selflessness).
The expression of this at fine mental formation is Upppada (beginning), Thithi (rising to a peak) and Bhanga (dissolution) of one thought moment to another with similar beginning, crescendo and dissolution; i.e; in other words “a state of flux” of mental formation and dissolution.
This formation does not end at physical death but extends into the next round of existence in Bhava. The mental process is described as a stream (Bhavanga Sota) which invariably accompany the being.
One experiences only one thought moment at any particular time. No two thought moments coexist. Each thought moment hangs onto some kind of object. No consciousness arises without an object either physical or mental.
When a person is fast asleep and is in a dreamless state he experiences a kind of consciousness which is more passive than active (note no mention about subconsciousness in Abhidhamma akin to Freudian analysis). It is similar to consciousness at the time of conception and at the final moment of death.
This type of consciousness in Abhidhamma term is Bhavanga. Like any other consciousness it consists of  genesis (Uppada) steady state or static (Thiti) and cessation (Bhanga). Arising and perishing it flows on like a stream not remaining the same for two consecutive thought moments. According to Abhidhamma, two types of (conscious and subconscious) of consciousness does not exist.
Bhavanga is not a sub-plane but a continuous stream of existence.
In Abhidhamma the word that aptly describe the state of the mind is Javana (running, no exact English rendering). This Javana thought moment lasts seven thought moments or at times of death five thought moments. Javana state is arrested by Thadarammana when an object (physical or mental) of attention is registered by the thought process and consists of two thought moments.
The death occurs immediately after the Cuti consciousness. 
Cuti and Patisandhi are continuous, within the same thought moment and there is no room for Untharbhava in Abhidhamma!
It lapses into Bhavanga sota of enormity (of Samsara) which each one owns of his own, with neither beginning nor end.
A super being cannot pardon actions (Kusala or Akusala) of a being or arrest this process.
Though, with death, the physical body disintegrates and the flow of consciousness temporarily ceases yet the stream is not annihilated as the Kammic force that propels it remains.
Death is  only a prelude to rebirth.
As Patisandhi (relinking) is the initial thought moment of life so Cuti the final thought moment. They are the entrance and exist of a particular life. Cuti occurs between Javana and Patisandhi, Thadarammana and Patisandhi and Bhananga and Patisandhi.
So the Samsara is the conditional existence (sort of cause and effect process) of beings, all inclusive (not only human but Deva and Preta included) and the goal of Buddhist Practice is to strive for Unconditional Existence of the Mental Culture (not a zero sum game or state) of Bliss without attachment (Tanha).
Way to achieve this is by one’s own effort of Meditation (not just meditation) with clear understanding of the above premises of Anitta, Dukka and Anatma.
Mind’s response to sense organ’s perception of an impulse as part of an object (Kaya/Rupa) of attention sets in a chain reaction.
1. Impulse has to be above the threshold value.
2. That causes to arise sensation from the sense object.
3. Perception of that sensation as agreeable, disagreeable or neutral.
4.Volitional (Cetana) attachment (Tanha) to that Citta (i.e; awakening of the life stream (Bhavanga sota)  of continuity).
5. Momentary focus of attention to that state of Mind.
6. Brings to life the mental phenomenon associated with that state of mind (within the Mind or arise from sense organ).
7. Attention to the same until another (Citta) thought process begins.
Upppda, Thiti and Bhanga process recurs in an undulating form in each thought moment of the present. In terms of the life process, Patisandhi, Bhavanga and Cuti operate, in the ever recurring Samsara Cycle.
Javana is the most important of all where the free will operates and the action (good or bad) falls into either Kusala or Akusala Kamma. One owns or inherits the merits or demerits of his or her action or deed.
Thought process has 17 thought moments and Javana has 7 thought moments and Tadarammana has two thought moments and the rest of the eight thought moments are given separate names starting from Atita Bhavanga to Votthappana ending in Javana and Tadarammana.
This in essence embodies the basic tenets of Abhidhamma but does not include all the finer classifications.
Summary;
1. Bhavanga sota
2. Bhavanga uppaccheda
3. Bhavanga calana
4. Avarjana (focus of attention)
5. Tadarammana (focus of attachment)
6. Javana (there is no proper English rendering of this word)
7. Kusala and Akusala (or Kriya of the Arhaths)
Uppada, Thiti and Banga of the thought moment or process ensues with extreme rapidity.
8. Bhavanga sota.