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VB.Net supports single inheritance + multiple interface implementation.

Class Animal
    Public Property Name As String
    Public Sub New(name As String)
        Me.Name = name
    End Sub
    Public Overridable Function Sound() As String
        Return "..."
    End Function
End Class

Class Dog
    Inherits Animal
    Public Sub New(name As String)
        MyBase.New(name)
    End Sub
    Public Overrides Function Sound() As String
        Return "woof"
    End Function
End Class

• Inherits BaseClass — single base
• Overridable (base) + Overrides (derived) — virtual methods
• MyBase — refers to the parent (like super in Java)
• MustInherit Class — abstract; can't instantiate
• MustOverride Sub/Function — abstract method
• NotInheritable Class — sealed (no further inheritance)
• NotOverridable — locks an override down

Polymorphism:

Dim a As Animal = New Dog("Rex")
Console.WriteLine(a.Sound())   ' "woof" — virtual dispatch

Interfaces:

Interface IGreetable
    Function Hello() As String
End Interface

Class English
    Implements IGreetable
    Public Function Hello() As String Implements IGreetable.Hello
        Return "hi"
    End Function
End Class

Note Implements IGreetable.Hello — VB requires you to name which interface method this implements (allows different naming).

Multiple interfaces — comma-separated after Implements.