Reversing a string is easily done by putting its characters in a:

1. Reversal needs the last character to come out first. 2. One structure gives exactly that order for free. 3. Reversing a string is easily done by putting the characters of a string in a stack. 4. So the answer is a stack. _Source: syllabus Computer Science, Ch 3 'Stack' and Ch 4 'Queue'_