When you buy or sell a financial instrument—whether it's a stock, bond, mutual fund unit, or derivative—you are executing a trade. Every trade has two sides: a buyer and a seller, and both agree on a price and quantity at a specific point in time. Trades on Indian exchanges like the NSE and BSE are matched electronically through order books and are subject to SEBI's regulations on fair execution. The trade date marks when the agreement is made, while the settlement date is when the actual exchange of money and securities happens.