Nested loops are a helpful tool in programming. They let you run one loop inside another loop. This is great for working with multi-dimensional data, like tables or grids.

How They Work

• Outer Loop: This loop sets how many times the inner loop will run.
• Inner Loop: This loop goes through its own set of actions every time the outer loop runs.

For example, let’s say you want to print a multiplication table. You could use an outer loop to go through the numbers 1 to 10. Then, for each number, the inner loop would also go through the numbers 1 to 10, figuring out and showing the product of the two numbers.

When to Use Nested Loops

You should use nested loops when:

1. Working with Grids: You have data in two-dimensional forms like tables or grids.
2. Comparing Data: You need to look at or process sets of data together.

But be careful not to use too many nested loops. Too much nesting can make your program slower, especially with large datasets. For example, two nested loops can lead to a time complexity of $O(n^2)$, which means it takes a lot longer to run.

In short, nested loops are an important part of programming. Just remember to use them wisely to keep your code running efficiently!