Visual Basic is a tool that allows you to develop Windows (Graphic User Interface - GUI) applications. The applications have a familiar appearance to the user. Development environment is a set of software development tools, presented as a unified environment in which the software developer can efficiently work.
It consists of:
a. Toolbox
b. Object Browser
c. Code Window
d. Project Explorer
e. Properties Window
f. Form Layout Window
g. Immediate Window
h. Locals Window
i. Watch Window
j. Data View Window
Basic Program Structure
Because a Visual Basic application is based on objects, the structure
of its code closely models its physical representation on screen.
By definition, objects contain data and code. The form that you see
on screen is a representation of the properties that define its appearance
and intrinsic behavior. For each form in an application, there is
a related form module (with file name extension .frm) that contains
its code.
Each form module contains event procedures - sections of code where you place the instructions that will execute in response to specific events. Forms can contain controls. For each control on a form, there is a corresponding set of event procedures in the form module. In addition to event procedures, form modules can contain general procedures that are executed in response to a call from any event procedure.
Code that isn't related to a specific form or control can be placed in a different type of module, a standard module (.BAS). A procedure that might be used in response to events in several different objects should be placed in a standard module, rather than duplicating the code in the event procedures for each object.
A class module (.CLS) is used to create objects that can be called from procedures within your application. Whereas a standard module contains only code, a class module contains both code and data — you can think of it as a control without a physical representation.