The marketing mix refers to the set of controllable tactical marketing tools that a firm uses to influence demand for its products, traditionally categorized into four elements: product, price, place, and promotion. Product encompasses any market offering that satisfies consumer needs, price is the monetary value placed on a product or service, place involves the distribution channels that make products accessible, and promotion includes activities that communicate product benefits to customers. The document also mentions the evolution of the marketing mix and introduces an expanded model that includes additional elements relevant to service marketing.