Final answer:
The essential characteristics of job-order costing are a wide variety of unique products and products that incur different costs, which is especially applicable in custom manufacturing, construction, and professional services.
Step-by-step explanation:
The essential characteristics of job-order costing are seen in environments that produce a wide variety of unique products, where products incur different costs. This contrasts with process costing, where products are more uniform and the costs per unit are similar.
Job-order costing is applied in situations such as custom manufacturing, construction, or professional services, where each job is distinct and may require a different combination of materials, labor, and overhead. Hence, costs are tracked to specific jobs so that profitability and efficiency can be assessed for each individual project rather than for a series of identical or similar products.