A woman becomes lawful for a man by contracting marriage.
There are two kinds of marriages: (i) Permanent marriage and (ii) Fixed time marriage . In a permanent marriage the period of companionship is not fixed and it is for ever. The woman with whom such a marriage is concluded is called daima (i.e. a permanent wife). In a fixed time marriage (Mut'ah) the period of companionship is fixed, for example, when matrimonial alliance is concluded with a woman for an hour. or a day, or a month, or a year, or more. However, the period fixed for the marriage should not exceed the ordinary lives of the spouses, because in that case the marriage will be treated to be a permanent one. This sort of fixed time marriage is called mut'ah or sigha.