E-commerce involves the buying and selling of goods and services over the internet. It provides several advantages over traditional commerce like lower costs, 24/7 access, and a larger customer base. Popular examples of e-commerce include business-to-business sites like Intel selling to Asus, business-to-consumer retailers like Flipkart in India, and consumer-to-consumer sites like eBay. While e-commerce provides many benefits, it also faces disadvantages such as security risks, inability to examine products physically, and delays in receiving goods.