Delta measures how much an option’s premium is expected to change for a ₹1 (or 1-point) move in the underlying’s price. Call Delta is positive (moves with the underlying); Put Delta is negative (moves opposite to the underlying).
Delta and Moneyness
Deep ITM options have Delta close to 1.00 (Call) or -1.00 (Put); ATM options are close to 0.50 or -0.50; deep OTM options approach 0. Delta is also often used informally as a rough approximation of the probability an option expires ITM.
Related Reading
See the full deep-dive lesson, with worked examples and a probability interpretation, in Delta Explained: How Options Move With the Stock Price.