Accounting periods are the

Accounting periods are the periods in which you perform your operations.Accounting periods are closed so as to ensure that no accounting entries can be passed in that period after they are clsoed.Suppose you have issued your results without closing your accounting periods and then you chnage some entries in that period thus in turn misleading the public at large.So it is important to close your accounting periods.Also, if accounting periods in Ap are not closed it shall not allow you to run GL.Prior to closng the periods it is important to ensure that all your invoices are validated and no hold exists on any one of them.If hold exists it shall not allow you to run GL.