what is header in post request flutter code example

Example: flutter http.post headers

Future<dynamic> get(String url) async {
    //Pass headers below 
    return http.post(url, headers: {"Authorization": "Some token"}).then(
        (http.Response response) {
      final int statusCode = response.statusCode;
      LogUtils.d("====response ${response.body.toString()}");

      if (statusCode < 200 || statusCode >= 400 || json == null) {
        throw new ApiException(jsonDecode(response.body)["message"]);
      }
      return _decoder.convert(response.body);
    });
  }