Data analytics can provide useful insights for marketing, sales, and e-commerce by helping businesses understand customer demographics and responses to advertising, determine the most effective marketing strategies, and chart how product desirability depends on context. When used for marketing, business analytics offers benefits like gaining a full view of customers, personalizing engagements, sharpening social media strategies, and engaging customers in real-time, but can also pose risks like data misinterpretation, inappropriate data collection methods, and high expenses.