Find all permutations of a given string.

To find all permutations of a string, a common and efficient approach is to use recursion. The core idea is to fix one character at a time and then recursively find all permutations of the remaining characters. This can be visualized as building the permutations step-by-step. For a string of length 'n', you can iterate through each character, place it at the first position, and then find all permutations of the remaining 'n-1' characters. This process is repeated until the string is empty or has only one character, at which point the permutation is complete.