In Keyword in C#

using System;
using System.Linq;
using System.Text;
using System.Collections;
using System.Data;
using System.Xml;
using System.IO;
using System.Diagnostics;
using System.Collections.Generic;
using System.Data.SqlClient;

namespace BlogProject
{

class Program
{
static void Main(string[] args)
{
Int32[] a = { 1, 2, 3, 4, 5 };
foreach (int b in a)
{
Console.WriteLine(b);
}
Console.ReadLine();
}
}
}