Pascal's triangle is a triangular array of numbers where each number is the sum of the two directly above it. The triangle starts with a single "1" at the top, and each subsequent row contains one more number than the previous row. The first few rows are: ``` 1 1 1 1 2 1 1 3 3 1 1 4 6 4 1 ``` Each row corresponds to the coefficients in the binomial expansion of a + b raised to the power of n. For example, the third row (1, 2, 1) represents the coefficients of (a + b)², which expands to a² + 2ab + b².