Besides necessary cases of dealings, marriage is the only legitimate way for men and women to get in contact with each other. The proper way for Islamic marriage is that a man introduces himself to the father or the guardian of the woman he chooses in order to obtain his approval for marrying her. Getting the approval of the father or the guardian does not entitle the man for any right over the woman until the marriage is validly concluded. After getting the approval of the guardian and before the conclusion of the marriage contract this period is an engagement period during which each of the man and the woman has to treat the other as a stranger. Only after the marriage contract is concluded they become husband and wife and have full rights of the marital relationship.
Therefore, valid marriage contract has to meet specific conditions in order to be valid.