Where to put the business logic

[eluser]Unknown[/eluser]
Hi. I'm a new user with CodeIgniter and I have a doubt about where I need to put my files.

I think I understand perfectly what is the purpose of the controlers, models and views but in my application I have some "business logic"

At the moment, I am putting in the "third_party" folder and I am loading it in the "autoload" file using the "require_once" PHP statement.

But I think that CodeIgniter must provide a more logical solution to this, isn't it?

Again, sorry about my poor English y thanks very much por your patient and effort.