night help: I’ve been trying to learn VB.NET since last night and I’ve been doing quite well up until now. - Help.com

For loops are generally used when you know the number of times you want to do something. In contrast, a Do While loop repeats a set of instructions an unknown number of times until a condition is met. Anything you can do with a For loop can be done with a Do While loop, but the For loop is designed to be simple for the common situation in which you want to do an action a specific number of times. For loops are found in many, many programming languages. While they have different syntax in different languages, the generally have three things in common:

1) they define an index variable that is incremented (or decremented) each time that you go through the loop.
2) they set an initial value for the index variable, so that it starts with a value you provide
3) they set the final value of the index variable to stop at (or after, depending on the language)

One of the main uses of for loops is to perform something many times, once on each member of a data structure like an array. You will learn about arrays in Chapter 7 of the tutorial, but if you have ever worked with matrices in math class the idea will be very familiar. For now, just know that if you want to do something a certain number of times a For loop is a good choice.

Loop is pretty useful in programming. For a simple example, if you want to perform a lookup on a table to sum up certain columns, you have to use Loop.