As per Perrault & McCarthy: “A marketing plan is a written statement of a marketing strategy and the time-related details for carrying out the strategy. It should include: (1) what marketing mix will be offered and to whom (target)(2) what company resources will be needed; and (3) what results are expected”
There is another defiention by P. Kotler & K. Keller: “A marketing plan is a written document that summarizes what the marketer has learned about the marketplace and indicates how the firm plans to reach its marketing objectives…The marketing plan operates at two levels: strategic and tactical. The strategic marketing plan lays out the target markets and the value proposition…The tactical marketing plan specifies the product, price, channel and communication”
We consider Philip Kotler as the father of marketing He is the author of over 60 marketing books, including Marketing Management, Principles of Marketing, Kotler on Marketing, Marketing Insights from A to Z, Marketing 4.0, Marketing Places, Marketing of Nations, Chaotics, Market Your Way to Growth, Winning Global Markets, Strategic Marketing for Health Care Organizations, Social Marketing, Up and Out of Poverty, and Winning at Innovation, if you really need to understand marketing you should read his books .
A good marketing plan should answer 4 simple questions the Marketing Plan should answer:
Where are we now?
Where do we want to be in the future?
How are we going to get there?
What results should we get from this Marketing Plan?
To answer the first one you need to do analysis either internal one and external one considering all factor of you own business ,industry ,product and competition, if we know where we are we can now where we are heading .
For 2nd one is simply our marketing strategy either to expand in our segment, develop new product or line extensions .for 3rd one you need to play with your marketing mix (product, price, promotion, and place)
The final question will clarify the objective with metric to evaluate the plan and decide if you need any correction action ,keep in mind to use smart objective The letters S and M usually mean specific and measurable. Possibly the most common version has the remaining letters referring to achievable, relevant and time-bound.