diff --git a/strings/capitalize.py b/strings/capitalize.py
new file mode 100644
index 000000000..2a84a325b
--- /dev/null
+++ b/strings/capitalize.py
@@ -0,0 +1,27 @@
+from string import ascii_lowercase, ascii_uppercase
+
+
+def capitalize(sentence: str) -> str:
+    """
+    This function will capitalize the first letter of a sentence or a word
+    >>> capitalize("hello world")
+    'Hello world'
+    >>> capitalize("123 hello world")
+    '123 hello world'
+    >>> capitalize(" hello world")
+    ' hello world'
+    >>> capitalize("a")
+    'A'
+    >>> capitalize("")
+    ''
+    """
+    if not sentence:
+        return ''
+    lower_to_upper = {lc: uc for lc, uc in zip(ascii_lowercase, ascii_uppercase)}
+    return lower_to_upper.get(sentence[0], sentence[0]) + sentence[1:]
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()