Can you post a link to the description of the challenge?

In general, recursion works by reducing the complexity of a problem through each iteration.

Perhaps the palindrome question says that numbers like 12344321 are palindromes. If we want to check through code though, how would we reduce the size of this problem recursively?
Maybe by checking if 234432 is a palindrome?
And maybe that checks if 3443 is a palindrome
And maybe that checks if 44 is a palindrome

So if you can imagine that a problem set 12344321 can be reduced recursively then you can try to code that.

Recursion an excellent way of solving arbitrary problems. And it has nothing to do with programming. Computers are just really good at doing the same thing over and over again, which makes recursion a great problem solving technique.

A tree is recursive data type. What does this mean? Just as a recursive function makes calls to itself, a recursive data type has references to itself. A tree is one of the many data structures, which is naturally recursive , i.e. recursive by its design itself.

Similarly by definition, a word which is 0 or 1 letters is a palindrome. The recursive step palindrome function is to check if the first letter and last letter are equal. If they are equal, then remove the first and last character and check the resulting string.