The research was based on the definition of(that the open) and its types in the Holy Qur’an، and it mentioned in the research the places of obligation and permissibility in that the open one in addition to giving some Qur’an evidence about these types and the research was carried out on two topics .the first topic included the types of open once . the second topic included a difference of some grammarians regarding that the open one and concluded the research with several results that the researcher reached with a list containing the most important sources and references.
Keywords: The open one, Types of An, Grammarians opinions