The StringComparer returned by the StringComparer.InvariantCultureIgnoreCase property compares strings in a linguistically relevant manner that ignores case, but it is not suitable for display in any particular culture. Its major application is to order strings in a way that will be identical across cultures.

The invariant culture is the System.Globalization.CultureInfo object returned by the System.Globalization.CultureInfo.InvariantCulture property.

The StringComparer.InvariantCultureIgnoreCase property actually returns an instance of an anonymous class derived from the StringComparer class.