Data types refer to an extensive system used for declaring variables or functions of different types. 
The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted.
Data Types Available in VB.Net
VB.Net provides a wide range of data types. The following table shows all the data types available:
| Data Type | Storage Allocation | Value Range | 
|---|
| Boolean | Depends on implementing platform | True or False | 
| Byte | 1 byte | 0 through 255 (unsigned) | 
| Char | 2 bytes | 0 through 65535 (unsigned) | 
| Date | 8 bytes | 0:00:00 (midnight) on January 1, 0001 through 11:59:59 PM on December 31, 9999 | 
| Decimal | 16 bytes | 0 through +/-79,228,162,514,264,337,593,543,950,335 (+/-7.9...E+28)with no decimal point; 0 through +/-7.9228162514264337593543950335 with 28 places to the right of the decimal | 
| Double | 8 bytes | -1.79769313486231570E+308 through -4.94065645841246544E-324, for negative values 4.94065645841246544E-324 through 1.79769313486231570E+308, for positive values
 | 
| Integer | 4 bytes | -2,147,483,648 through 2,147,483,647 (signed) | 
| Long | 8 bytes | -9,223,372,036,854,775,808 through 9,223,372,036,854,775,807(signed) | 
| Object | 4 bytes on 32-bit platform 8 bytes on 64-bit platform
 | Any type can be stored in a variable of type Object | 
| SByte | 1 byte | -128 through 127 (signed) | 
| Short | 2 bytes | -32,768 through 32,767 (signed) | 
| Single | 4 bytes | -3.4028235E+38 through -1.401298E-45 for negative values; 1.401298E-45 through 3.4028235E+38 for positive values | 
| String | Depends on implementing platform | 0 to approximately 2 billion Unicode characters | 
| UInteger | 4 bytes | 0 through 4,294,967,295 (unsigned) | 
| ULong | 8 bytes | 0 through 18,446,744,073,709,551,615 (unsigned) | 
| User-Defined | Depends on implementing platform | Each member of the structure has a range determined by its data type and independent of the ranges of the other members | 
| UShort | 2 bytes | 0 through 65,535 (unsigned) | 
Example
The following example demonstrates use of some of the types:
Module DataTypes
   Sub Main()
      Dim b As Byte
      Dim n As Integer
      Dim si As Single
      Dim d As Double
      Dim da As Date
      Dim c As Char
      Dim s As String
      Dim bl As Boolean
      b = 1
      n = 1234567
      si = 0.12345678901234566
      d = 0.12345678901234566
      da = Today
      c = "U"c
      s = "Me"
      If ScriptEngine = "VB" Then
         bl = True
      Else
         bl = False
      End If
      If bl Then
         'the oath taking
          Console.Write(c & " and," & s & vbCrLf)
          Console.WriteLine("declaring on the day of: {0}", da)
          Console.WriteLine("We will learn VB.Net seriously")
          Console.WriteLine("Lets see what happens to the floating point variables:")
          Console.WriteLine("The Single: {0}, The Double: {1}", si, d)
      End If
      Console.ReadKey()
   End Sub
End Module
When the above code is compiled and executed, it produces following result:
U and, Me
declaring on the day of: 12/4/2012 12:00:00 PM
We will learn VB.Net seriously
Lets see what happens to the floating point variables:
The Single:0.1234568, The Double: 0.123456789012346
The Type Conversion Functions in VB.Net
VB.Net provides the following inline type conversion functions:
| S.N | Functionss & Description | 
|---|
| 1 | CBool(expression) Converts the expression to Boolean data type.
 | 
| 2 | CByte(expression) Converts the expression to Byte data type.
 | 
| 3 | CChar(expression) Converts the expression to Char data type.
 | 
| 4 | CDate(expression) Converts the expression to Date data type
 | 
| 5 | CDbl(expression) Converts the expression to Double data type.
 | 
| 6 | CDec(expression) Converts the expression to Decimal data type.
 | 
| 7 | CInt(expression) Converts the expression to Integer data type.
 | 
| 8 | CLng(expression) Converts the expression to Long data type.
 | 
| 9 | CObj(expression) Converts the expression to Object type.
 | 
| 10 | CSByte(expression) Converts the expression to SByte data type.
 | 
| 11 | CShort(expression) Converts the expression to Short data type.
 | 
| 12 | CSng(expression) Converts the expression to Single data type.
 | 
| 13 | CStr(expression) Converts the expression to String data type.
 | 
| 14 | CUInt(expression) Converts the expression to UInt data type.
 | 
| 15 | CULng(expression) Converts the expression to ULng data type.
 | 
| 16 | CUShort(expression) Converts the expression to UShort data type.
 | 
Example:
The following example demonstrates some of these functions:
Module DataTypes
   Sub Main()
      Dim n As Integer
      Dim da As Date
      Dim bl As Boolean = True
      n = 1234567
      da = Today
      Console.WriteLine(bl)
      Console.WriteLine(CSByte(bl))
      Console.WriteLine(CStr(bl))
      Console.WriteLine(CStr(da))
      Console.WriteLine(CChar(CChar(CStr(n))))
      Console.WriteLine(CChar(CStr(da)))
      Console.ReadKey()
   End Sub
End Module
When the above code is compiled and executed, it produces following result:
True
-1
True
12/4/2012
1
1