In the first place, we would like to stress that a woman’s “mahram is a person whom she is never permitted to marry because of their close blood relationship (such as her father, grandfather, great-grandfather, etc., and her son, grandson, great-grandson, etc., her paternal and maternal uncles, her brother, brother’s son and sister’s son), or because because of radaa’ah or breastfeeding (such as the brother and husband of the woman who breastfed her), or because they are related by marriage (such as the mother’s husband, the husband’s father, grandfather, etc., and the husband’s son, grandson, etc..).
List of Mahrams is given in the following Qur`anic verse:
“And tell the believing women to lower their gaze and be modest, and to display of their adornment only that which is apparent, and to draw their veils over their bosoms, and not to reveal their adornment save to their own husbands or fathers or husbands fathers, or their sons or their husbands’ sons, or their brothers or their brothers’ sons or sisters sons, or their women, or their slaves, or male attendants who lack vigor, or children who know naught of women’s nakedness. And let them not stamp their feet so as to reveal what they hide of their adornment. And turn unto Allah together, O believers, in order that ye may succeed.” (An-Nur: 31)”
Thus, A Mahram is a near relative that a person cannot marry. For example, the father, the mother, the brother, the sister, the aunt, the uncle, the grandfather, the grandmother etc…