The Intersect method or operator is used to combine multiple collections or lists into a single collection or list and return common elements from both collections.

Syntax

var result = collection.Intersect(collection2);

Example

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

public class Program
{
 public static void Main()
 {
  List<string> count1= new List<string>() { 'UK', 'Australia', 'India', 'USA' };
  List<string> count2 = new List<string>() { 'India', 'UAE', 'Canada', 'UK', 'China', 'Pok' };

  List<string> list = count1.Intersect(count2).ToList();
  list.ForEach( country => Console.WriteLine(country) );

  Console.ReadLine();
 }
}

Output

UK

India