pandas StringDtype is an extension dtype for textual Series. Unlike object, it prevents unrelated Python objects such as lists, dictionaries, or None from entering a string column. section 9.0
Choosing missing values
For a StringDtype Series, use pd.NA rather than NaN. pd.NA is designed to work across pandas dtypes, while NaN is a float value. This gives string data a consistent pandas missing-value representation. section 9.0
StringDtype was added in pandas 1.0.0 and is intended to become pandas’ standard string type. Its documentation still describes it as experimental, so implementations and parts of the API may change. section 9.0
