Absolutely! It all falls under that broad ill-defined umbrella.
The actual question is a poor one, which is probably why the responses are equally poor. It's why I can simply say "yes" because "SEO" could encapsulate any number of things.
Many people consider SEO to define on-page optimisation only, and they refer to any off-page optimisation as SEM. So in that instance, the answer would be a simple "no".
It's all about perspective