ListThis code uses the Add method to add the numbers 1 and 2 to the list, and then uses the indexer (denoted by the square brackets) to retrieve the second item from the list (which has an index of 1 since lists are zero-indexed). The List class is part of the .NET Framework class library, which is distributed with Visual Studio. Therefore, you don't need to install any additional packages to use it in your C# code.numbers = new List (); numbers.Add(1); numbers.Add(2); int secondNumber = numbers[1];