VB Language

Visual Basic, the name makes me feel that it is something special. In the History of Computing world no other product sold more copies than Visual Basic did. Such is the importance of that language which clearly states how widely it is used for developing applications. Visual Basic is very popular for it's friendly working (graphical) environment. Visual Basic. NET is an extension of Visual Basic programming language with many new features in it. The changes from VB to VB .NET are huge, ranging from the change in syntax of the language to the types of projects we can create now and the way we design applications. Visual Basic .NET was designed to take advantage of the .NET Framework base classes and runtime environment. It comes with power packed features that simplify application development.

Briefly on some changes:

The biggest change from VB to VB .NET is, VB .NET is Object-Oriented now. VB .NET now supports all the key OOP features like Inheritance, Polymorphism, Abstraction and Encapsulation. We can now create  classes and objects, derive classes from other classes and so on. The major advantage of OOP is code reusability
The Command Button now is Button and the TextBox is TextBox instead of Text as in VB6
Many new controls have been added to the toolbar to make application development more efficient
VB .NET now adds Console Applications to it apart from Windows and Web Applications. Console applications are console oriented applications that run in the DOS version
All the built-in VB functionality now is encapsulated in a Namespace (collection of different classes) called System
New keywords are added and old one's are either removed or renamed
VB .NET is strongly typed which means that we need to declare all the variables by default before using them
VB .NET now supports structured exception handling using Try...Catch...Finally syntax
The syntax for procedures is changed. Get and Let are replaced by Get and Set
Event handling procedures are now passed only two parameters
The way we handle data with databases is changed as well. VB .NET now uses ADO .NET, a new data handling model to communicate with databases on local machines or on a network and also it makes handling of data on the Internet easy. All the data in ADO .NET is represented in XML format and is exchanged in the same format. Representing data in XML format allows us for sending large amounts of data on the Internet and it also reduces network traffic when communicating with the database
VB .NET now supports Multithreading. A threaded application allows to do number of different things at once, running different execution threads allowing to use system resources
Web Development is now an integral part of VB .NET making Web Forms and Web Services two major types of applications

Namespaces

A namespace is a collection of different classes. All VB applications are developed using classes from the .NET System namespace. The namespace with all the built-in VB functionality is the System namespace. All other namespaces are based on this System namespace.

Some Namespaces and their use:

System: Includes essential classes and base classes for commonly used data types, events, exceptions and so on
System.Collections: Includes classes and interfaces that define various collection of objects such as list, queues,
hash tables, arrays, etc
System.Data: Includes classes which lets us handle data from data sources
System.Data.OleDb: Includes classes that support the OLEDB .NET provider
System.Data.SqlClient: Includes classes that support the SQL Server .NET provider
System.Diagnostics: Includes classes that allow to debug our application and to step through our code
System.Drawing: Provides access to drawing methods
System.Globalization: Includes classes that specify culture-related information
System.IO: Includes classes for data access with Files
System.Net: Provides interface to protocols used on the internet
System.Reflection: Includes classes and interfaces that return information about types, methods and fields
System.Security: Includes classes to support the structure of common language runtime security system
System.Threading: Includes classes and interfaces to support multithreaded applications
System.Web: Includes classes and interfaces that support browser-server communication
System.Web.Services: Includes classes that let us build and use Web Services
System.Windows.Forms: Includes classes for creating Windows based forms
System.XML: Includes classes for XML support

Assemblies

An assembly is the building block of a .NET application. It is a self describing collection of code, resources, and metadata (data about data, example, name, size, version of a file is metadata about that file). An Assembly is a complied and versioned collection of code and metadata that forms an atomic functional unit. Assemblies take the form of a  dynamic link library (.dll) file or executable program file (.exe) but they differ as they contain the information found in a type library and the information about everything else needed to use an application or component. All .NET programs are constructed from these Assemblies. Assemblies are made of two parts: manifest, contains information about what is contained within the assembly and modules, internal files of IL code which are ready to run. When programming, we don't directly deal with assemblies as the CLR and the .NET framework takes care of that behind the scenes. The assembly file is visible in the Solution Explorer window of the project.

An assembly includes:

• Information for each public class or type used in the assembly – information includes class or type names, the classes from which an individual class is derived, etc
  
• Information on all public methods in each class, like, the method name and return values (if any)
  
• Information on every public parameter for each method like the parameter's name and type
  
• Information on public enumerations including names and values
  
• Information on the assembly version (each assembly has a specific version number)
  
• Intermediate language code to execute
  
• A list of types exposed by the assembly and list of other assemblies required by the assembly 

Image of a Assembly file is displayed below.