Chebulic myrobalan - Haritaki

Ignites the digestive fire making even micro nutrients available to the body
 Rejuvenates the body
 Increases the bulk of the body
 A very good nervine tonic
 A tonic for eyes
 Enhances the longevity of the person
 Nourishes the body up to the tissue level
 Scrapes out the unnecessary deposits and toxins out of the body
 Cardiac tonic

Common Name:
Chebulic myrobalan (Eng.)

Sanskrit Name:
Haritaki- Means one which is originated from Hari's (God's) home or
Which is green in nature; here green stands for faith and fertility. or
That carries away all the illnesses from the body
Abhaya- That makes a person fear free from all the diseases and discomforts
Pathya- Means it is an all time good herb for everyone
Amrita- Means it is like nectar for the body

Lt. Name:
Terminalia chebula- Combretaceae

What mythology says about the plant:
It is said that when Indra (king of deities in Hindu mythology) was drinking nectar in heaven, a drop of the fluid fell on the earth and produced Haritaki.

Bio energetics:
Rasa (Taste)- Haritaki contains all the six tastes except the Lavana (salty one)
Guna (Characteristics)- Laghu (Light); Ruksha (Rough)
Veerya (Potency)- Ushna (Warm)
Vipaka (Post digestion effect)- Madhura (Sweet)
Prabhava (Special action an herb works which cannot be explained on logical parameters)- Tridoshahara (Pacifies all the three bio humors)

Actions according to Ayurveda:
Deepana- Haritaki ignites the digestive fire making even micro nutrients available to the body
Medhya- Haritaki is a very good nervine tonic
Rasayani- Haritaki Rejuvenates the body
Chakshushya- Haritaki is a tonic for eyes
Bruhamni- Increases the bulk of the body
Anulomani- Means it is having the property to digest the undigested Malas (Removable wastes of gastric system) and expel them out of the body through anus.
Aayushya/Vayasa sthapani- Means it enhances the longevity of the person
Paushtiki- Haritaki nourishes the body up to the tissue level
Lekhani- Haritaki scrapes out the unnecessary deposits and toxins out of the body
Hrudya- Cardiac tonic

Besides this Haritaki is also useful in management of respiratory discomfort, cough, urinary disorders (including Diabetes mellitus), hemorrhoids, skin diseases, edematous conditions, assimilatory disorders, chronic fever,  vomiting, hiccough, heart diseases, jaundice (And other liver and spleen disorders) renal stones and anemia.

Medicinal value:
Haritaki has proven gastrokinetic effect i.e. it helps in moving the contents of stomach earlier. So it can be used after surgeries and as adjuvant with other drugs that interfere with gastric motility as antihistaminics, atropine like drugs.
One compound Chebulagic acid from Haritaki has shown antispasmodic action like that of Papaverine.
Haritaki can serve to act as an effective alternative to modern prokinetic drugs like metaclopramide.
Gallic acid and its ethyl ester, isolated from Terminalia chebula, displayed potent antimicrobial activity against several bacteria, including methicillin-resistant strains of Staphylococcus aureus (Sato et al 1998). A crude extract of Terminalia chebula is reported to have potent and broad spectrum antibacterial activity against human pathogenic Gram positive and Gram negative bacteria (Phadke and Kulkarni 1989).
Haritaki is reported to have antiherpes simplex virus type 1 activity (Kurokawa et al 1995). Haritaki  showed a significant inhibitory activity on the effects on human immunodeficiency virus-1 reverse transcriptase (el-Mekkawy et al 1995).
A water extract of Terminalia chebula was found to have an antifungal activity.

Precautions to be taken while taking Haritaki :
Haritaki should be sparingly used in the lean individuals, severe debility, while fasting, mental depression, and vitiated Pitta conditions and in pregnancy.

Useful part:
Fruits

Doses:
Powder- 3-6 gm

How to identify the Haritaki fruit with you is good:
The good fruit will go to the bottom of the glass having water in it.

Some important combinations with Haritaki:
Triphala churna; Abhayamodaka; Abhayarista; Abhayamodaka; Chitraka Haritaki; Agastya Haritaki; Danti Haritaki; Pathyadi curna; Pathyadi vati; Pathyadi kvatha; Vyaghri haritaki; Gandharva haritaki etc.

Some special notes about Haritaki:
If taken after meals Haritaki prevents imbalance of any of the humors due to bad food or drink.
Haritaki maintains the balance of all the three Doshas. When taken with Lavana (Rock salt) it pacifies the aggravated Kapha, with sugar the Pitta and with Ghruta (Indian clarified butter) the Vata.
Haritaki gives different results according to the mode of taking i.e. when chewed it ignites the digestive fire, when taken after making a paste it ensures the timely evacuation of the feces and when taken after roasting it balances all the three Doshas.
According to Charak, the most eminent Ayurvedic physician, Haritaki is the best fruit for rejuvenation and disease cure.
Haritaki is the drug of choice for rejuvenation for all the seasons. This is called as the "Ritu Haritaki". In rainy season it should be taken with Saindhava (Rock salt), in autumn with sugar, in early winter with Shunthi, in late winter with Pippali, in spring season with honey and in summer season it should be taken with Guda (Jaggery).

Additional Reading:
http://www.toddcaldecott.com/index.php/herbs/learning-herbs/361-haritaki 
http://thehealer.us/3730782-Haritaki.pdf
http://www.ncbi.nlm.nih.gov/pubmed/3225068
http://www.holistic-herbalist.com/terminalia-chebula.html