A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward (ignoring spaces, punctuation, and capitalization). For example, the word "level" is a palindrome because if you read it from left to right or right to left, it appears the same.
The word "palindrome" comes from the Greek roots "palin," meaning "again" or "back," and "dromos," meaning "way" or "direction." So, it literally means "running back again."