Mangala Gauri Vrata (vow) is taken in the month of Shravana (July/August). Gauri is a name of Parvati.
Unmarried women take the vow to have a husband like Shiva.
Married women take the vow for their husband’s well being.
Read about Mangala Gauri Vrata here
http://sushmajee.com/vrat-festivals/vrat/vrat-kathaa/mangalaa-gauree.htm