What is the difference between free-range and non- free-range?

In a conventional breeding farm, the birds are kept indoors. In an ‘outdoor’ farm, the birds also have access to an outdoor area. Free-range animals, i.e. those that can go outside, therefore have more space available and can experience more ‘natural’ conditions, however, there are downsides: they are more susceptible to disease due to exposure to the weather and contamination by wild birds. They are also much more expensive to breed.