泛型到底是干嘛的？有什么好处？小例子

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace Fanxing
{
    class Program
    {
        public delegate bool del(int x);

        static void Main(string[] args)
        {
            IList<Int32> i = new List<int> { 44, 33, 55 };

            List<Int32> j = new List<int> { 5, 2, 3 };

            //j.Add(9);
            j.Sort(new Comparison<int>(new hehe().Result));

            j.AddRange(new Int32[] { 11, 22, 33 }); //AddRange是指一个可以枚举的集合

            j.Where((int q) => { return q > 3; });  //没搞清楚


            int num = j.Find((int p) => { return p == 3; });
            //Console.WriteLine(num);

            Console.WriteLine("List.Find方法(参数委托类型)");
            Console.WriteLine(j.Find(delegate(int x) { return x > 2; }));
            Console.WriteLine("List.FindAll方法(参数委托类型)");
            Console.WriteLine((j.FindAll(delegate(int x) { return x > 2; }))[0]);
            Console.WriteLine("List.Find方法(参数是另外定义的方法)");
            Console.WriteLine(j.Find(new hehe().show));
            Console.WriteLine("List.Find方法(参数是兰姆达表达式)");
            Console.WriteLine(j.Find((int x) => { return x > 3 && x < 5; }));
            Console.WriteLine((j.Where((int x) => { return x > 3 && x < 8; })));   //如果条件不止一个，该怎么写
            //Console.WriteLine("{0},{1},{2},{3}", j[0], j[1], j[2], j[3]);
            Type t = j.GetType();

            List<test> c = new List<test>();
            c.Add(new tson());
            c.Sort();

            //Console.Write(c[0].GetType());
            Console.ReadLine();
        }
    }
    public class test
    {
    }

    public class tson : test
    {

    }

    public class hehe
    {
        public int Result(int x, int y)
        {
            if (x > y)
                return 0;
            else
                return 1;
        }

        public bool Get(int x)
        {
            x = 22;
            return true;
        }

        public bool show(int x)
        {
            if (x > 3)
                return true;
            else
                return false;
        }
    }
}