why do they have two front doors in USA to get in there home one out side and the other main door with locks on it?

I've never seen a home in the USA with 2 front doors.

Not everywhere does but its nice too have a storm door with alot of glass on it. In nice weather you can leave the front door open and get lots of light streaming in. In bad weather it helps insulate the door.

Apartment complexes have two because there's a hallway that the individual apartment doors open up onto.

Most homes here have a main door and a screen door (which converts to a storm door in winter) on their houses. The storm door/screen door is a lightweight aluminum door and does nothing other than let you open your MAIN door (the one with the locks) and still keep out the mosquitoes, but allows fresh air to come in. It keeps the pets inside too. Mine has screens and a sliding glass piece that comes down in winter and keeps snow from building up against the main door along the bottom (and protects the keyholes from filling with ice/snow).

Two reasons - One is for a grand entrance when receiving guests, the second is to move in massive furniture.

I m not from usa but we have two doors as well - creates a buffer zone in winter

some states require it especially on rentals, the whole idea is that if the thief can't get in quickly(and unlocking two locks takes time) they will move on to the next place with one lock

All houses in the United States do not have two doors in order to enter their house.

There are many reasons individuals have two doors

#1. They just want the doors.(They find two doors attractive)

#2. The doors were on the house when they purchased the house

#3. For safety and protection reason

#4. For weather reasons

#5. To use as a means of storing heavy boots, shoes and clothing for clod weather.

I hope this has been of some benefit to you, good luck.

"FIGHT ON"

Your literacy is so poor that I am having trouble understanding your question. If you mean 'why do houses have two sets of doors' the answer is that in colder areas a vestibule can make a massive difference to heat loss. As this is not a security issue, you would not lock both sets of doors. Leaving the outer set unlocked allows packages to be put inside the vestibule out of the rain/snow. Not unique to the US by the way, my parents' house in London is configured that way.

Personally I never lock my doors at all but that is because I live in an area where this is unnecessary.

no idea why they have locks cause apparently they never lock them