Marketing Plan: In this you perform, precise activities which helps in achieving the goals and objectives you are targeting at. Here, you plan how you will promote the product/service? What are the specific areas of promotion? What would be the budget of this plan execution? Etc. Plus, you also estimate the ROI of this marketing strategy.
Imagine if you can do all these and manage all these in a marketing plan? Systematic, organized, well thought, innovative and captured all your pertinent business information, don't you find having a marketing plan is useful for your business?