How does CultureInfo.InvariantCulture and DateTime to String works in c#

How does CultureInfo.InvariantCulture and DateTime to String works in c#

DateTime dateParameter= System.DateTime.Now;
DateTime currentDateTime = dateParameter;
string formattedIdentifier = dateParameter.ToString(System.Globalization.CultureInfo.InvariantCulture);
string dateParameterAsString = dateParameter.ToString(); 
string formattedIdentifier3 = dateParamter.ToString("yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture); 
string formattedIdentifier2 = dateParamter.ToString("yyyyMMdd"); 

2020-02-23