For every failure of human pursuit, a Dosha (defect) in the horoscope is necessarily held responsible. Some of these Doshas are very commonly known, whereas some of these Doshas are not that common and thus not that widely known. Whatever these Doshas in the kundali may be, they definitely have their say in the horoscope. Pandit Lokesh Pariyal Ji, the top-rated astrologer in India, explained in detail about these all Doshas in Astrology. Here are the excerpts of the interview:
A Dosha in Vedic astrology means a combination of malefic planets that would not let the positive things in the horoscope to fructify. It is like a blemish on a horoscope. A number of these negative Doshas in a horoscope can be casting their ill effect on the native simultaneously. Therefore, it is essential to identify these Doshas, know their activation timing, and apply the proper karma correction that could prevent these Dosha from getting activated.
There can be countless Doshas in a horoscope, but only the dreaded few are often discussed. The Kaal Sarpa Dosha, Pitra Dosha, Mangal Dosha, Nadi Dosha, Putra Dosha, Grahan Dosha, Bhandhan Yoga, Paap Kartari Dosha, Guru Chandal Dosha, Angarak Dosha, Gandalmool Dosha, Shani Dosha, Shrapit Dosha, Kemdhrum Dosha, etc. are most commonly known Doshas.
These Dosha are necessarily formed in a Kundli because of the misdeeds and misfortunes one had in his/her previous birth(s). These Dosha pronounce a bad time/event in one's life but, knowing them beforehand can solve the problem to a great extent by Pandit Lokesh Pariyal Ji.
https://www.panditlokeshpariyal.com/kundli-greh-dosha-specialist-india.html
