The break statement terminates the closest enclosing loop or switch statement in which it appears. If it is used in the nested inner loop, it will jump out the inner loop and return the control to the outer loop.

Break Simple Loop

using System;
int i = 0;
while (i < 10)
{
    if(i == 5) break;

    Console.WriteLine($" {i} ");

    i += 1;
}

Output:

 0 
 1 
 2 
 3 
 4 

Break Nested Loop

using System;
int i = 0;
while (i < 10)
{
    int j = 0;

    while (j < i)
    {
        if(j > 5) break;

        Console.Write($" {j} ");

        j += 1;
    }

    Console.WriteLine();

    i += 1;
}

Output:

 0 
 0  1 
 0  1  2 
 0  1  2  3 
 0  1  2  3  4 
 0  1  2  3  4  5 
 0  1  2  3  4  5 
 0  1  2  3  4  5 
 0  1  2  3  4  5