Promotion is a very important component of marketing as it can boost brand recognition and sales.
Advertising typically covers communication methods that are paid for like television advertisements, radio commercials, print media, and internet advertisements. In contemporary times, there seems to be a shift in focus offline to the online world.
Public relations, on the other hand, are communications that are typically not paid for. This includes press releases, exhibitions, sponsorship deals, seminars, conferences, and events.