It may happen that you have to define a lot of variable of some type, and you want the possibility to later change their type without manually change the declaration of all of them. You can’t use a simple Find & Replace, because you don’t want to change the type of ALL the variables of that original type. The solution is to create an alias for a type, and use it in the variable declarations. When you later want to change the type of the variables, you just change the type that has that alias. Here’s how you declare an alias:

' define the alias in VB.NETImports DefaultType = System.Double' // define the alias in C#using DefaultType = System.Double;

From now on, just declare the variables using the alias instead of the real type name:

Dim var As DefaultType = 1.2