Indirect materials are supplies used in the production process that cannot be directly traced to a specific product. These materials support the manufacturing process but do not become part of the finished product. Examples include lubricants for machinery, cleaning supplies, and tools used in production. In accounting, indirect materials are categorized as part of overhead costs. They are essential for maintaining operations but are not included in the direct costs of goods sold. Proper management of indirect materials helps businesses control expenses and improve overall efficiency in the manufacturing process.