Egress windows are a great way to let the light into what is usually a dark area in your home, but here are two types of windows in basements: ventilation windows and egress windows. And there's quite a difference between the two.
Ventilation windows are what you will find in unfinished basements. They provide fresh airflow when needed.
On the other hand, egress windows are required in basement bedrooms or any finished areas in the basement. They must provide an emergency exit for whatever reason may arise. Egress windows must be installed according to the national code.