A SIP, or Systematic Investment Plan, is a way of investing a fixed amount of money into a mutual fund automatically at regular intervals — almost always monthly — rather than investing a large sum all at once. You set it up once with your bank, and the chosen amount is auto-debited and invested on the same date every month, much like a recurring bill payment but in reverse.
SIPs are popular in India because they make investing a disciplined habit that doesn't depend on trying to time the market correctly. Since you're buying units every month regardless of whether prices are high or low, your purchase cost naturally averages out over time — a benefit known as rupee cost averaging. SIPs also suit salaried individuals well, since a portion of each month's income can be automatically channelled into long-term goals without requiring active decisions each time.