What is Early and Late Binding?

Dim oXL As Object
 Set oXL = CreateObject("Excel.Application")

Dim oXL As Object
 Set oXL = GetObject(, "Excel.Application")

Dim oXL As Excel.Application
 Set oXL = New Excel.Application

//early binding:
public create_a_foo(*args) {
 return new Foo(args)
}
my_foo = create_a_foo();

//late binding:
public create_something(Class klass, *args) {
  klass.new_instance(args)
}
my_foo = create_something(Foo);

# early binding:
def create_a_foo(*args)
  Foo.new(*args)
end
my_foo = create_a_foo

# late binding:
def create_something(klass, *args)
  klass.new(*args)
end
my_foo = create_something(Foo)