Visual Basic application source code is structured into ''module'' files with ''.vb'' suffix. By default, Visual Studio creates a separate module file for each form in an application containing the code to construct the form. For example, the code to create a form called ''Form1'' will be placed in a module file named ''Form1.Designer.vb''. Similarly, any code that has been defined by the developer to handle events from comtrols controls in the form will be placed by Visual Studio into a module file called ''Form1.vb''.
When writing additional Visual Basic for an application, the code should ideally be logically grouped to together with other source code in a module file. When we say ''logically grouped'' we mean that the code should be grouped with other code of a similar nature. For example, code to work with files might be placed in a module called FileIO.vb, while mathematical procedures might all reside in a file name Math.vb. The idea is to ensure Visual Basic code is placed in a file where it make sense for it to be located. This will differ between applications, but it is worth investing the time to ensure code is well structured as doing so makes subsequent maintenance of the code by you or other developers much easier.
