Perfectly competitive firms relate to firms in a perfectly competitive market, which is characterized by high competition since there are many suppliers in the market. Monopoly firm refers to a firm in a monopoly market, which is characterized by a low level of competition since there is a limited supply in the market.

No, perfectly competitive firms and monopolies do not have incentives to advertise their product. In a perfectly competitive market, there is perfect knowledge about the product and the suppliers can sell all the product they produce. Thus, advertising their products would increase their marginal cost, which does not make sense since the firm can sell all the products it can produce. Firms in a monopoly market also do not have an incentive to advertise since they have a significant share of the market; thus most people know the product, and it would not be beneficial to advertise the product.