The SOSTAC Marketing Planning Model is a model for marketing planning that takes into account the four stages of the customer lifecycle. It is divided into two parts - the first part, which focuses on customer acquisition and retention, and the second, which focuses on customer development. The SOSTAC Marketing Planning Model covers all aspects of marketing planning from customer acquisition to customer retention to customer development. The model also includes a detailed timeline for each stage of the lifecycle. This article provides an overview of this marketing planning model and how it can be used in your company's strategy.