A palindrome is a number, word, or sentence that reads the same from left to right and right to left. Use PalindromeQ, its options, and other string-related low-level functions to test for palindromic words and sentences.
This is an English palindrome.
The name Anna is also a palindrome, but you need to ignore the capitalization.
PalindromeQ["Anna", IgnoreCase -> True]
Use Decapitalize as an alternative to make the first character be lowercase.
The French verb "rêver" is a palindrome as well, but you need to ignore the diacritic.
PalindromeQ["rêver", IgnoreDiacritics -> True]
Use RemoveDiacritics to process the verb instead.
With palindromic sentences, you also generally need to process the initial string.
sentence = "Now, sir, a war is won!";
StringDelete[sentence, PunctuationCharacter | Whitespace]
StringDelete[sentence, PunctuationCharacter | Whitespace]; PalindromeQ[%, IgnoreCase -> True]