You have several options for managing laying hens and broilers (meat birds). Your choice of method might be determined by space limitations, the number of chickens you plan to raise, and climate.
Chickens need 10 square feet per bird if the coop is their only space, or 4 square feet per bird if they can free range during the day, or have a run to access during the day that allows them 10 square feet per bird. Generally speaking, the more generous you can be with space for your hens, both inside the coop and in the run, the happier they will be.
A Coop and Run
If you're planning to build a coop and run for your chickens, allow a minimum of 10 square feet per bird in the run. 4-foot high chicken wire and metal T-posts work well for permanent chicken runs. You can also use plastic step-in posts. If you're serious about predator protection, bury the bottom of the chicken wire 12 inches deep.
You can choose to keep the birds completely enclosed in a coop (and if you have harsh winters, this may be the hens' choice once the snow flies). Or, you can have a coop that opens onto a fenced (and sometimes netted on top) run. This is probably the most common method.
If you truly want to raise your birds on pasture, but don't want them to completely free range, consider using a chicken tractor. This method involves a movable pen, often called a chicken tractor, that is floorless so the chickens can graze on grass. Sometimes the chicken tractor is the birds' only living space - this method is especially useful for meat birds, who don't wander far from food and water anyway and thus don't need much "range."
Or, a floored or floorless movable coop can be used with electric net fencing, or electronet, around it. This is more commonly used for larger flocks and laying hens. The coop can contain roosts and nest boxes, but still be able to be moved to fresh ground. The fencing is also moved to contain the birds' pasture to different areas of the farm.
Some farmers just use a trailer or other permanent or movable chicken coop and allow the hens to range around it without any containment at all. Most of the time with free roaming hens, you'll still want to close them in the coop at night. By providing roosts in the coop, you can increase the likelihood that they will all go into the coop once night falls.
One of the drawbacks of free roaming your flock is that they can be more vulnerable to predators. However, some farms have perimeter fencing or a livestock guardian dog or dogs to ward off potential seekers of a free-roaming chicken dinner.