Personal selling involves an oral presentation given by a salesperson who approaches an individual or a group of potential customers. Personal selling allows for two-way communication and relationship building that can aid both the buyer and the seller in their goals. Personal selling is most commonly seen in business-to-business marketing (e.g.: selling machinery to a factory, selling paper to a print shop), but it can also be found in business-to-consumer marketing (e.g.: selling cars at a dealership). 
Marketing entails product development, market research, product distribution, sales strategy, public relations, and customer support. Marketing is necessary in all stages of a business's selling journey, and it can use numerous platforms, social media channels, and teams within their organization to identify their audience, communicate to it, amplify its voice, and build brand loyalty over time.
It's critical that your marketing department uses their understanding and analysis of your business's consumers to offer suggestions for how and where to sell your product. Perhaps they believe an ecommerce site works better than a retail location, or vice versa. Or, maybe they can offer insights into which locations would be most viable to sell your product, either nationally and internationally.
This refers to how the product gets to the customer; the distribution channels and intermediaries such as wholesalers and retailers who enable customers to access products or services in a convenient manner. This third P has also sometimes been called Place or Placement, referring to the channel by which a product or service is sold (e.g. online vs. retail), which geographic region or industry, to which segment (young adults, families, business people), etc. also referring to how the environment in which the product is sold in can affect sales.  5 Digital Marketing Skills to Master for 2020 & Beyond