Extracted from the website of Buddhist Vajrayana Charity Funds Association and translated (五蘊、十二處、十八界) into English:

Five Aggregates
Twelve Entrances    Eighteen Realms

For Buddhists, the Five Aggregates, Twelve Entrances, Eighteen Realms are the laws of differentiation for everything. The major principle is ‘Selflessness’ (or ‘No Self’), which is ‘Emptiness’. ‘Selflessness’ (or ‘No Self’) refers to ‘No physical matter has independent self existence and remains unchanged forever’.
‘Five Aggregates’	－	the formation of sentient beings
‘Twelve Entrances’	－	the conditions that lead to the arising of mind consciousness
‘Eighteen Realms’	－	the origin of recognition
Five Aggregates
Aggregate is to accumulate. The old translation of Five Aggregates is Five Yin.
(1) A concise explanation of the Five Aggregates:
1. Form Aggregate – substance(or material) form
2. Sensation Aggregate – feeling
3. Thought Aggregate – presentment, association of ideas
4. Volition (Mental Formations) Aggregate – mind and behavior
5. Consciousness Aggregate – perception consciousness, to understand (the explanation) and to            distinguish (the difference)
(2) Five Aggregates are divided into two categories:
1. One is substance (form), one is mind (non-form /name).
2. Sentient being is formed by substance and mind, the former Aggregate is substance            (or material form), and the latter four Aggregates are mind.
(3) The aspect of recognition can be classified into two types:

A. The subject having the ability to recognise	B. The object that can be recognised
1. Form Aggregate
2. Sensation Aggregate – the object that is      recognised	Worldly people take it to be  self-possession
3. Thought Aggregate
4. Volition (Mental Formations) Aggregate
5. Consciousness Aggregate – the self that has      the ability to recognise	Worldly people always take it to be the  self

Twelve Entrances
•	Entrance, meaning the door of growth.
•	Sentient beings rely on the Six Sense Organs (also known as Six Roots) and the link from the Six Sense Objects (also known as Six Domains); the combination of sense organ and sense object generates mind consciousness.
•	Six Sense Organs combine with Six Sense Objects to become twelve entrances, which is the doorway of growth for mind consciousness, that is where mind consciousness develops.
•	Six Sense Organs (Eye Ear Nose Tongue Body Mind) are the six types of the nervous system, Six Sense Objects (Form Sound Smell Taste Touch Thought) are the six types of the counterpart images.

Six Sense Organs	Six Sense Objects
Eye Sense Organ	Form Sense Object
Ear Sense Organ	Sound Sense Object
Nose Sense Organ	Smell Sense Object
Tongue Sense Organ	Taste Sense Object
Body Sense Organ (Touch nerve)	Touch Sense Object (Object of Touch)
Mind Sense Organ (Perception Nerve)	Thought Sense Object (Object of Perception)

	(Note)	For example, the word sense organ of the Eye Sense organ, is not the eye ball, it is the material spread around the eye ball that has the power of vision, called Pure Colour, also known as nervous tissue.

•	The Mind Sense Organ has the function of controlling the whole five sense organs, Thought Sense Object comprises the form, sound, smell, taste and touch of the five sense objects.
Eighteen Realms
•	Sense Organ interacts with Sense Object to form recognition.
•	Six Sense Organs, Six Sense Objects and Six Recognitions combine to form Eighteen Realms. Realm has the meaning of cause, that is the seed; this explains that there are numerous conditions for generating mind recognition so as to turn down one reason alone.

Six Sense Organs (To face)	Six Sense Objects (To generate)	Six Recognitions (To understand & distinguish)
Eye Realm	Form Realm	Eye Recognition Realm
Ear Realm	Sound Realm	Ear Recognition Realm
Nose Realm	Smell Realm	Nose Recognition Realm
Tongue Realm	Taste Realm	Tongue Recognition Realm
Body Realm	Touch Realm	Body Recognition Realm
Mind Realm	Thought Realm	Mind Recognition Realm