If / Then / Else / End If

Conditionally execute a block of statements depending on the value of an expression

Syntax: 

If condition Then [statements] [Else  else statements] End If 

condition Required. A test condition
statements Optional. A block of statements to be executed when the condition is True
else statements Optional. A block of statements to be executed when the condition is False

Example:

If a>b And c<d Then
   x=1
Else
   x=2
End If

Also See: