The term "free-range" is typically used to refer to any animal that is permitted to roam free through fields, rather than being confined to a cage or enclosure. Free-range chickens are chickens that have access to grass for at least some of the day, and free-range eggs are the eggs that free-range chickens produce.
Though the USDA has strict guidelines for what constitutes a free-range chicken, there are no such guidelines for free-range eggs, and so the term can be used at will, and is sometimes abused by merchandisers. Cage-free is another term with the same meaning — many eggs at grocery stores are labeled "free-range" or "cage-free," and can cost more than twice as much as traditional eggs from caged hens.
Typically, free-range hens are healthier and have a more nutritious diet than hens that are kept in cages constantly. As a result, eggs that truly are "free-range eggs" tend to have harder shells, more golden yolks, and a better flavor than standard eggs.
Many people buy free-range eggs for ethical reasons, because they are under the impression that free-range hens are treated more humanely than battery hens. Unfortunately, this is not always the case. In many commercial free-range egg operations, the hens are debeaked and intentionally starved, so that they continue to lay eggs, just as battery hens are.
The best place to purchase free-range eggs is from a small farm or a farmer's market. Many farms raise hens and sell free-range eggs from chickens that are not abused. If you have the space, you might also consider raising your own chicks and keeping hens for their eggs. This way, you will be able to wake up to delicious free-range eggs every morning. This is a substantial commitment, however. By doing this, you will need to make sure that you have adequate shelter for the chickens, and that you will be able to provide them with high-quality food every day.
Making the switch to free-range eggs is a growing trend throughout the world. Google's corporate headquarters recently decided to use only free-range eggs in its cafeteria, and Canada's University of Guelph agricultural college has committed to serving only free-range eggs in their dining hall.