Working capital refers to funds used in a business's day-to-day operations. It is the difference between current assets and current liabilities, and includes inventory, cash, and accounts receivable that can be converted into cash within one year. Maintaining adequate working capital is important for liquidity and profitability. Too much working capital ties up funds unnecessarily, while too little prevents a business from operating efficiently and taking advantage of opportunities. Proper management of working capital levels is crucial for smooth business functioning.