Intraday trading is not for investment purposes but to earn profit from the movement of stocks. Intraday trading is a lot riskier due to uncertainty in the market, price volatility, and volume fluctuations in the stocks. In the intraday, stocks can be bought on a margin basis. Think of it as buying more quantity of shares for less amount, so you have to settle the trade on the same day.
We will understand margin-based intraday trade with an example; consider the share price of Airtel is Rs.550, then to buy 100 shares of Airtel, you will need Rs.55,000 (550X100), but if you buy 100 shares of Airtel as an intraday trade, you will need only Rs.5,500 (Considering 10X margin) which is around 1/10th of Rs.55,000. Margin may vary from stock to stock and broker to broker.