Breakpoints are an important tool for debugging a JavaScript program. A breakpoint is a special marker that allows you to pause the execution of your code at a specific point in the program, so that you can inspect the state of the variables and the values of the code at that moment. This can help you identify bugs and errors in your code more easily.

In most debugging tools, breakpoints are added using a graphical interface or a special command-line syntax. Here's an example of how to add a breakpoint using Chrome DevTools:

1. Open Chrome and navigate to the page that contains the JavaScript program you want to debug.

2. Press F12 to open the Developer Tools window.

3. Find the Sources tab in the left-hand column of the DevTools window.

4. Select the JavaScript file that you want to debug from the list of sources.

5. Find the line number where you want to add a breakpoint, and click the blue square icon next to the line number to add a breakpoint.

6. Now, when you run your program, it will pause at the breakpoint you added.

When your code hits a breakpoint, the debugger will stop executing and open a new window or tab that displays information about the state of the program, including the values of variables and the call stack. This can help you identify where the bug is occurring and what might be causing it. Here's an example of what the Debugger window might look like:

In this example, we've defined a JavaScript program that attempts to divide `x` by `y`, which will cause a TypeError because division by zero is not allowed. We've added a breakpoint at the line where the division occurs, and when we run the program, it will pause at the breakpoint.

$eval(function() {
  var x = 10;
  var y = 0;
  console.log(x / y);
});

{type: 'Breakpoint', lineNumber: 2, columnNumber: 4}

When you click on the Debugger window, you'll see information about the state of the program at the time of the breakpoint.

This tells you that the breakpoint was at line 2 (the division operation), and the current column is 4 (in this case, the first character of the `/` symbol). You can use this information to identify where the bug is occurring and what might be causing it.

In conclusion, breakpoints are a powerful tool for debugging JavaScript programs. By adding breakpoints at key points in your code, you can pause execution and inspect the state of the program at that moment, which can help you identify bugs and errors more easily.