Object Model

There are three main VBE objects
VBProject - This is the entire set if VBA Modules and references associated with a workbook or document.
VBComponent - This is the individual component within a VBProject (ie a module or a userform)
CodeModule - This is the actual module "Module1" or "Module2" etc.

VBE Object

This is the top level object of the Visual Basic Editor
The VBE refers to the Visual Basic Editor, which includes all the windows and projects that make up the editor.

Dim obVBAEditor As VBIDE.VBE 
Set obVBAEditor = Application.VBE 

VBProject

A VBProject corresponds to one of the top level items in the Project Explorer
A VBProject contains all the code modules and components of a single workbook.
One workbook has exactly one VBProject. The VBProject is made up of 1 or more VBComponent objects.
You can also iterate through the VBProjects collection

Dim obVBProject As VBIDE.VBProject 
Set obVBProject = Application.VBE.VBProjects(2) 
Set obVBProject = Workbooks(1).VBProject 

When programming the VB Editor it is very useful to know which project is currently highlighted in the Project Explorer
This is given by the ActiveVBProject property

Dim obVBP AS VBIDE.VBProject 
Set objVBP = Application.VBE.ActiveVBProject 

Note that this project is the project the user is currently editing in the VB Editor and is not related to the active workbook or document

VBComponent

A VBComponent is one object within the VBProject.
A VBComponent is a code module, a UserForm, a class module, one of the Sheet modules, or the ThisWorkbook module.
A VBComponent is of one of the following types, identified by the Type property. The following constants are used to identify the Type.
The numeric value of each Enumeration Constant is shown in parentheses.
vbext_ct_ClassModule (2): A class module to create your own objects.
vbext_ct_Document (100): One of the Sheet modules or the ThisWorkbook module.
vbext_ct_MSForm (3): A UserForm. The visual component of a UserForm in the VBA Editor is called a designer.
vbext_ct_StdModule (1): A regular code module. Most of the procedures on this page will work with these types of components.

Dim objVBComponent As VBIDE.VBComponent 
Set objVBComponent = ActiveWorkbook.VBProject.VBComponents("Module1") 
Set objVBComponent = objVBProject.VBComponents("Module1") 

The Userforms, standard modules, class modules and code modules behind the worksheets and workbook are all VBComponents objects.
Each VBComponent object corresponds to one of the lower level items in the Project Explorer tree.
A specific VBComponent can be located through the VBComponents collection of a VBProject.
Hence to find the VBComponent that represents the UserForm1 form in Book1.xls you should use:

Dim obVBC As VBIDE.VBComponent 
Set obVBC = Workbooks(").VBProject.VBComponents("UserForm1") 

The name of the VBComponent that contains the code behind the workbook, worksheets and charts is given by the CodeName property of the related Excel object
Hence to find the VBComponent for the code behind the workbook you can use:

Set obVBC = Workbooks(1).VBProject.VBComponents(Workbooks(1).CodeName) 

and for a specific worksheet you could use:

Set obVBC = Workbooks(1).VBProject.VBComponents(Workbooks(1).Worksheets(2).CodeName) 

Note that the name of the workbook's VBComponent is usually "ThisWorkbook" in the Project Explorer
Do not rely on this name
If the user has chosen a different language for the Office User Interface, it will be different.

When developing Add-ins for the VBE you often need to know the VBComponent that the user is currently editing.
This is given by the SelectedVBComponent property of the VBE.

Dim obVBC As VBIDE.VBComponent 
Set obVBC = Application.VBE.SelectedVBComponent 

Each VBComponent has a Properties collection, corresponding approximately to the list shown in the Properties window of the VBE when the VBComponent is selected in the Project Explorer.
One of these is the Name property.

Sub ShowNames 
   With Application.VBE.SelectedVBComponent 
      Debug.Print .Name & ": " & .Properties("Name") 
   End With 
End Sub 

For most VBComponent objects, the text returned by .Name and .Properties("Name") is the same.
However for the VBComponent objects that contain the code behind workbooks, worksheets and charts.
Properties("Name") gives the name of the Excel object (workbook, worksheet or chart).
You can use this to find the Excel object that corresponds to the item that the user is working on in the VBE or the Excel workbook that corresponds to the ActiveVBProject.

CodeModule

All the VBA code for a VBComponent is contained in a CodeModule object
A CodeModule is the VBA source code of a VBComponent. You use the CodeModule object to access the code associated with a VBComponent. A VBComponent has exactly one CodeModule.
There is only one CodeModule for each VBComponent
Every type of VBComponent has a CodeModule - check !!!

Dim objCodeModule As VBIDE.CodeModule 
Set objCodeModule = ActiveWorkbook.VBProject.VBComponents("Module1").CodeModule 
Set objCodeModule = objVBComponent.CodeModule 

CodePane

This provides access to the user's view of a code module.
A CodePane is an open editing window of a CodeModule.
This allows you to identify things like the section of a code module that is currently visible on the screen or the text the user has selected.
You can identify which CodePane is currently being edited by using the ActiveCodePane property

Dim obCP AS VBIDE.CodePane 
Set obCP = Application.VBE.ActiveCodePane 

Subroutines, Functions and Properties

In the code and descriptions on this page, the term Procedure means a Sub, Function, Property Get, Property Let, or Property Set procedure.
The Extensibility library defines four procedures types, identified by the following constants.
The numeric value of each Enumeration Constant is shown in parentheses.
vbext_pk_Get (3). A Property Get procedure.
vbext_pk_Let (1). A Property Let procedure.
vbext_pk_Set (2). A Property Set procedure.
vbext_pk_Proc (0). A Sub or Function procedure.

Events

The Office object model defines individual CommandBar controls that have their own Click events
The VBE does expose a CommandBarEvents object that has a Click event with the following event handler.

Dim WithEvents CmdBarEvents As CommandBarEvents 
Private Sub CmdBarEvents_Click(ByVal CommandBarControl As Object, handled As Boolean, CancelDefault As Boolean) 

And a reference to a CommandBarControl is passed to VBE.Events.CommandBarEvents to register the event handler for that CommaneBarControl:

Set CmdBarEvents = Application.VBE.Events.CommandBarEvents(CmdBarItem) 
link - cpearson.com/excel/VbeMenus.aspx 

Designer

Userforms have a graphical interface and a code module
The Designer object provides access to the graphical part

It is possible to modify the code in your code modules dynamically via code. The main procedures / functions are:
InsertLines (line,code) - inserts a line or lines of code at a specific location in a block of code. (example)
Lines (startline,nooflines) - to obtain the code on a particular line
DeleteLines (line,code) - deletes a single line or specified range of lines (example)

Methods

ProcStartLine - returns the line at which the specified procedure begins
ProcBodyLine - returns the first line of the procedure
Lines - returns the specified line of code

Project Locked properties