With the purpose of better understanding business plans, this final paper discusses its importance and components, as well as the steps for successful implementation. This paper covers the theoretical aspect of marketing and start-up entrepreneurship, as well as the practical part of business plans. The theoretical part consists of an introduction, two chapters and four subchapters in which the importance of marketing, the role of the market and the concept of start-up companies are explained in more detail. Furthermore, the practical segment includes the very elaboration of the business plan. It gives knowledge about the goals, mission and vision of a given company and what strategies it implements in order to achieve them, then what services it offers for which target group, how it distributes them and so on. It is shown how to calculate salaries, sales forecast, income and expenses, loan repayment and many others. It can be concluded that every company, if it wants to operate successfully, needs a quality business plan, as well as a well-organized implementation of the same.