Gauri is another name for Parvati, the female consort of Shiva, one of the principal deities from Hindu Trinity (Trimurti). She is also known by the name Annapurna - translated as nourishment provider. Moons too represents Mother and nourishment. It stands to valid reason that a planetary Yog named after her name involves a very well-placed and highly benefic Moon.
The Definition and Description from Phaladipika goes as follows.
Definition
"When the Moon is in its own or exaltation sign and falls in an angle or trine and is aspected by Jupiter, the Yog formed is called Gauri Yog."
Description
"Natives born in Gauri Yog in their Birth chart have an appealing personality, born of an illustrious family, and a friend of the sovereign. Their sons possess noble character. Their looks are like those of a lotus flower; success always kissing their feet and praised by one and all."
Explanation
Gauri Yog bestows the blessings of Divine Mother Gauri in variety of ways. There are so many nourishment factors associated with this Yog clearly mentioned in the description given in Phaladipika.
- Born of an illustrious family - Strong family background is such an affluent nourishing factor.
- A friend of the Sovereign - This is some thing not many people have, a very strong friend as a support.
- Sons possess noble character - Having noble children ensures so much for old age.
Astrologically, Moon with such a good backing, like in another lunar Yog Chandra Adhi, is a very good factor for any Birth chart. Here Moon is fundamentally strong by being in its own or exaltation sign and in good houses like angles(1st, 4th, 7th, 10th) or trines(1st, 5th, 9th). In addition to it, Moon flourishes under the aspect Great benefic Jupiter.