Indirect materials are items used in a production process that are not typically part of the finished product. These items serve as inputs to a larger manufacturing process and include items such as raw materials, energy, transportation, packaging, maintenance supplies, utilities, and office supplies. In purchasing, indirect materials are considered non-essential components without which production cannot take place but do not directly add value to the end product. Indirect materials need to be carefully estimated so that procurement professionals can avoid overspending on unnecessary supplies or risk production delays due to inadequate inventory.