diff --git a/DIRECTORY.md b/DIRECTORY.md
index d0c4469..bca02fb 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -23,6 +23,7 @@
     * Strings
       * [Anagram Checker](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/anagram_checker.rb)
       * [Jewels And Stones](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/jewels_and_stones.rb)
+      * [Palindrome](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/palindrome.rb)
       * [Remove Vowels](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/remove_vowels.rb)
     * [Two Sum](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/two_sum.rb)
     * [Two Sum Ii](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/two_sum_ii.rb)
diff --git a/data_structures/arrays/strings/palindrome.rb b/data_structures/arrays/strings/palindrome.rb
new file mode 100644
index 0000000..1ebcfbe
--- /dev/null
+++ b/data_structures/arrays/strings/palindrome.rb
@@ -0,0 +1,44 @@
+# Challenge name: Valid Palindrome
+#
+# Given a string s, determine if it is a palindrome,
+# considering only alphanumeric characters and ignoring cases.
+#
+# Example 1:
+# Input: s = "A man, a plan, a canal: Panama"
+# Output: true
+# Explanation: "amanaplanacanalpanama" is a palindrome.
+#
+# Example 2:
+# Input: s = "race a car"
+# Output: false
+# Explanation: "raceacar" is not a palindrome.
+#
+# Constraints:
+# 1 <= s.length <= 2 * 105
+# s consists only of printable ASCII characters.
+# @param {String} s
+# @return {Boolean}
+
+#
+# Approach 1: Brute Force
+#
+# Time Complexity:
+#
+def is_palindrome(s)
+  s.downcase
+end
+
+s = 'A man, a plan, a canal: Panama'
+puts is_palindrome(s)
+# Output: true
+# Explanation: "amanaplanacanalpanama" is a palindrome.
+
+s = 'race a car'
+puts is_palindrome(s)
+# Output: false
+# Explanation: "raceacar" is not a palindrome.
+
+s = 'ab_a'
+puts is_palindrome(s)
+# Output: true
+# Explanation: "aba" is a palindrome.
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