The two-pointer technique is an efficient way to solve array and string problems where two indices, often called 'pointers,' traverse the data from different directions. This technique is particularly useful for problems involving subarrays, pairs, or palindromes. For example, when looking for a pair of elements that sum to a target value in a sorted array, one pointer starts at the beginning and the other at the end, and they move toward each other until the target is found. The two-pointer approach reduces the time complexity of problems that would otherwise require nested loops, making it a powerful tool for solving array-related problems efficiently.