Use the
Distinct[
^] method from LINQ.
e.g.
IList<string> list = new List<string>
{
"a",
"b",
"A",
"c",
"d"
};
Console.WriteLine(String.Join(", ", list));
list = list.Distinct().ToList();
Console.WriteLine(String.Join(", ", list));
list = list.Distinct(StringComparer.InvariantCultureIgnoreCase).ToList();
Console.WriteLine(String.Join(", ", list));