Sharia law is an Islamic legal system which provides an Islamic alternative to secular models of governance. Women in societies governed by sharia have far fewer rights than women in the West.
Muslim-majority societies have varying degrees of sharia integrated into their law codes, but almost all use sharia to govern family affairs. Sharia courts also exist in a number of Western countries, particularly to adjudicate family law for Muslim citizens.
There is no one overarching authority which determines sharia, nor is there one conception of how women's rights fit into sharia law.
Different interpretations and laws depending on which of the four schools of Islamic Jurisprudence is being used, and the customs of the sects and country in question.
Many Muslim feminists argue that current interpretations of sharia that persist in oppressing women have no basis in Islam and are man-made misinterpretations of the sacred texts.
"I argue that Muslim family laws are the products of sociocultural assumptions and juristic reasoning about the nature of relations between men and women. In other words, they are ‘man-made’ juristic constructs, shaped by the social, cultural and political conditions within which Islam’s sacred texts are understood and turned into law." - Mir Hosseini, Ziba, Towards Gender Equality: Muslim Family Laws and the Sha'riah.