This method takes into account the casing rules of the current culture.
This method does not modify the value of the current instance. Instead, it returns a new string in which all characters in the current instance are converted to lowercase.
The casing operation that results from calling the string.ToLower method takes the casing conventions of the current culture into account. If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the string.ToLowerInvariant or string.ToUpperInvariant methods. This produces the same result in every culture (unlike the string.ToLower method) and performs more efficiently.