Integer overflow occurs when a number exceeds the maximum value a data type can hold, causing the result to wrap around or become negative. In competitive programming, this can lead to incorrect answers, especially in problems that involve large numbers, such as factorials, powers, or combinatorial calculations. To avoid overflow, use data types with larger capacities, such as `long long` in C++ or `BigInt` in JavaScript. In problems involving large results, modular arithmetic (i.e., taking the result modulo a prime number) is a common solution. For example, if the problem requires you to compute large sums or products, using a modulus ensures that your numbers stay within a manageable range. Understanding and handling integer overflow is essential in competitive programming, especially in problems involving large datasets.