Console.WriteLine (Regex.Match ("color", @"colou?r").Success); // True

Console.WriteLine (Regex.Match ("colour", @"colou?r").Success); // True

Console.WriteLine (Regex.Match ("colouur", @"colou?r").Success); // False

Match m = Regex.Match ("any colour you like", @"colou?r");

Console.WriteLine (m.Success); // True

Console.WriteLine (m.Index); // 4

Console.WriteLine (m.Length); // 6

Console.WriteLine (m.Value); // colour

Console.WriteLine (m.ToString()); // colour

Match m1 = Regex.Match ("One color? There are two colours in my head!",@"colou?rs?");

Match m2 = m1.NextMatch();

Console.WriteLine (m1); // color

Console.WriteLine (m2); // colours

foreach (Match m in Regex.Matches("One color? There are two colours in my head!", @"colou?rs?"))

Console.WriteLine (m);