Telemarketing is a method of direct marketing where sales representatives contact potential customers over the phone to promote products or services. This approach allows businesses to reach a wide audience quickly and can be used for various purposes, including sales, surveys, and customer feedback. Telemarketing can be conducted through cold calls, where representatives call individuals who have not expressed prior interest, or warm calls, where they reach out to existing customers. While it can be an effective sales strategy, it is often regulated to protect consumers from unwanted calls, leading to the establishment of laws like the National Do Not Call Registry.