Tally

A bill of materials (sometimes bill of material or BOM) is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, parts and the quantities of each needed to manufacture an end product.
To k now more about bill of material theoretically go here.
In simple a bill of material is the pre defined list of raw material required for manufacturing finish goods.
Remember this lesson is first step of creating manufacturing journal or manufacturing transaction in tally.