Basic objective of this article is to Define and Discuss on Long Run Costs. Here analysis Long Run Costs in economic perspective. A we know in the short‐run, some factors of production are fixed. Corresponding to each different degree of fixed factors, there would have been a different short‐run average total cost curve. The average total cost curve is one of many SATCs that can be obtained by varying the amount of the fixed factor, in this case, the amount of capital. Here also briefly discuss on Long‐run average total cost curve and Economies of scale with examples.