A horse should have the option to go in or out as he sees fit. A run-in shed is nice, or a stall with an attached paddock.
Horses undergoing frequent exercise require adequate rest, nutrition, water, shelter and companionship.
It is called "stable". A shelter exclusively for horses.
Animal shelter
stable
Horses survive on temperatures related to water conditions
Horses can survive in any weather so long as they have access to food, water and shelter. However recent research has found that horses seem to prefer temperatures right at 40 degrees Fahrenheit.It is at this temperature when a horses body does not have to try harder to keep itself cooler or warmer.
you can keep as many horses as you can care for depending on size of land and shelter
Wild ones use caves,trees, and anything that they can find that provides shelter
Horses that have not been provided a barn or shelter from their humans will take cover under trees or large shrubs or brush. Wild and ferel horses will do this also.
Their habitat should most likely be in a plain field or on a farm.
Depending on your budget you can get fancy or keep it simple. Most horses don't care that much. Horses need shelter from wind and rain. A simple 3 sided enclosure works fine for most horses. If you can afford it put rubber mats down. This will keep the bedding from getting wet if there is no wooden floor (as in a regular stall). Make sure it is big enough that he can lay down and not get wedged against a wall (caste). He will need a sturdy, safe fence, no barb wire, and a source of water. This is a very basic setup and will do nicely for most horses.
The habitat of wild horses is grass, mountains, family or herd, water from lakes, oxgen, shelter, and love.