Retail merchandising involves developing, pricing, supporting, and communicating a retailer's product assortment. It aims to offer the right products at the right time, price, and appeal. Effective merchandising requires analyzing sales, planning inventory levels, and controlling merchandise to optimize profitability. Key factors include forecasting demand, determining order quantities, tracking inventory levels using tools like open-to-buy, and evaluating product and vendor performance through methods such as ABC analysis and sell-through rates.