UEP Certified Cage-Free Guidelines were developed in 2006 to help assure hen welfare. Cage-free eggs are laid by hens that are able to roam vertically and horizontally in indoor barns and have access to fresh food and water. Cage-free systems vary from farm-to-farm, and can include multi-tier aviaries. They must allow hens to exhibit natural behaviors and include enrichments such as scratch areas, perches and nests. Hens must have access to litter, protection from predators and be able to move through a barn in a manner that promotes bird welfare.