An array contains a group of data with specific type, such as integer array, string array, double array etc.
int[] arr; int[] arr = new int[] {3,4,2,1,5,8}; string[5] arr;
string[] cities = new string[] {"Boston","New York","Houston"}; for (int i=0;i < cities.Length,i++) { string city = cities[i]; ... }
int[,] arr = new int[4,5]; //two dimentional array int[,] arr = new int[,] {{2,3,4},{11,12,24}};
class A { ... } A[] arr = new A[5];