Substring:A substring is a smaller part of a larger string. For example, in the string "hello", "ell" is a substring.
Palindrome: A palindrome is a word or phrase that reads the same forwards and backwards. For example, "racecar" is a palindrome.
Concatenation: Concatenation refers to combining two or more strings together to create one longer string. For example, concatenating "hello" and "world" would result in "helloworld".