Why do they call it an egress window?

e·gress
ˈēˌɡres/
noun

noun: egress

the action of going out of or leaving a place.

“direct means of access and egress for passengers”

synonyms:

departure, exit, withdrawal, retreat, exodus;
escape

“a means of egress”

• In Alberta, 3.77sq/ft. is the minimum requirement for clear space (or 0.35 m2 or 543 sq. /inches) This refers to the opening size, not the entire window size
• No window opening dimension (width or height) can be less than 15″
• Window wells if needed must be no less than a 30″ or 760 mm protrusion out from the foundation wall
• Window wells must be a minimum of 2″ above finished grade, but no more than 6″
• You require at least four feet from your foundation to your property line to install an egress compliant window well
  
• If your preferred basement window location ends up being underneath a cantilever, the cantilever cannot be more than 25.5 inches or 650 mm
• You cannot install egress compliant windows underneath decks unless there is 2.1 meters of head clearance
• To comply with a city permit, you cannot cut out more than 25% of the total wall length. You also need to have at least 1.2 meters clearance on one side of the home for the fire department. You have to be 36″ away from any exhaust vent. You need 6″ of drainage rock in the well. You need 6″ of clear space from the bottom of the window to the drainage rock.
• Sliding windows are most common. Casement and Hopper/Awning style windows can work so long as the sizing requirements are met.