Mangal Dosha, or Manglik Dosha, is an astrological condition in Vedic astrology where Mars (Mangal) is placed in certain houses (1st, 4th, 7th, 8th, or 12th) of a person's birth chart. It is believed to influence marital harmony, potentially causing challenges or delays in marriage. Remedies like specific rituals or gemstones are often recommended to mitigate its effects.