Advertising is one of the aspects of marketing. If you're selling a product, service or idea, advertising will help you promote these product service and idea to a more bigger audience which, hopefully, will become curious or interested in what you have to offer.
Marketing plays an important aspect in selling, and we know that selling more gives the company organization more revenues. This is the reason why in some companies, they have marketing departments to take care of the branding and advertisement of their products, services or ideas.
If you can't afford to set up a marketing department in your company, business or organization, you can still advertise and have marketing people work on your marketing strategies without paying for labor and overhead costs associated with a fully-staffed marketing department.
How? By getting the services of an advertising agency.
Even if you can afford to have a marketing department, having an advertising agency to work on your marketing strategies can still be advantageous at times. Advertising agencies just focus on advertising developments, trends, innovations and technologies and have the knowledge and expertise to learn more about the target market.
Whether it's in-house or outsourced, advertising and marketing are important so to answer the question of "should you advertise?" the answer's gonna be a big YES.