Under Muslim personal laws, marriages in violation of rules are known as Batil marriages. Those marriages which are in violation of conditions of affinity, fosterage etc are examples of Batil marriages (for example, marrying your mother’s sister). Batil is another way of saying that your marriage is void. A marriage can be annulled if it is void and it means that the marriage is not legally binding.
In certain circumstances, your marriage may be considered as Fasid or irregular. The prohibitions are temporary or a result of accidental circumstances – it is generally possible to rectify irregular marriages (for example, a marriage with no witnesses).0