Chickens come in different colours and sizes. Backyard, free-range chickens are probably safer if you choose ones that are not white, because they blend with the background better (unless you happen to live on a limestone cliff) and are not so easy for the predators to spot. Mottled ones, like the barred rocks, blend better than a solid colour. Chickens that are crosses of two breeds are stronger than a pure breed. If you start with unrelated chickens, have more than one rooster, and let them breed at random, the resulting multiple crosses of chickens will, after several generations, be the strongest of all. They will have selectively bred themselves to suit their own environment. The unsuitable crosses will have died out. However, they will also, more than likely, have bred out of themselves the very traits for which you got them in the first place, such as fantastic egg laying ability or quickly growing, large meat birds!

Old Fashioned Breeds versus Modern Crosses
The old fashioned breeds start laying at about 6 months old, and will stop laying each autumn (fall), when the weather turns cold and the days get short. If they have not started laying by the time winter comes, they will probably wait until spring. They will go into a molt, usually at the first cold snap in the weather, at which time they need extra energy to keep warm and grow new feathers, instead of producing eggs. In the temperate latitudes away from the equator they will start laying again in the spring. Since I live in Canada, I do not know what happens at the equator, where they neither get a cold season nor short days in the winter.
The true old-fashioned breeds will still go broody, usually in the spring, and want to sit on the nest to hatch chicks. Some of the modern 'old fashioned breeds' have been selectively bred to remove the desire to go broody, so if you want to hatch your own chicks, you need to make sure that you have a truly old fashioned bird whose genetics have not been messed with.
The modern crosses have had the desire to go broody bred out of them. The commercial egg layers have been bred to lay right through their first winter, and they keep going until they are around 18 months old, at which time they will stop laying and go into their first molt. The modern meat birds have been bred to grow really fast, and will not be able to lay viable eggs unless you restrict their feed and considerably increase the protein content of what they do eat. They are usually in the freezer before they are old enough to lay eggs anyway. They have, for the most part, lost their natural instinct to range for their food, unless they happen to be standing on it, at which point they will probably eat the grass at their feet, or whatever else happens to be there, edible or otherwise.
Something seems to get lost with all this selective breeding. The modern commercial cross meat birds have lost a lot of their thinking power - they are definitely on the not-so-bright side, especially when compared with the little layer hens.

Giant Breeds These are the meat birds. They don't lay too many eggs, but grow to a large size with plenty of meat on them. Cornish Giants and Jersey Black Giants are two of the giant breeds. The meat birds that you buy from a hatchery are usually a cross - see commercial crosses below.

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In 1997, I bought my first 200 day-old chicks, never having raised chicks in my life. I was born and bred in various cities throughout England. I have a B.Sc. in Physics, started out my working life as a computer programmer way back in the days of the dinosaurs, raised two children, and became a realtor for 12 years so that I could finish bringing up my children without babysitters. But all my life I have wanted to have a farm. As a child we had a holiday cottage on a farm in Herefordshire, and that was where the rot set in and I started yearning for a farm.
The first chicks that I bought were Warren Sex Links, which are one of the commercial laying hen crosses, and I believe they were a six way cross between a Leghorn and a Rhode Island Red. I raised them until they were mature and were laying almost one egg a day each. I was getting roughly 15 dozen eggs a day, which all had to be washed by hand. If, for some reason, I was unable to get to them one day, the next day I had to wash 30 dozen eggs. I was washing eggs in my nightmares. I decided that washing that many eggs every day by hand was, (pardon the pun), for the birds!
I put an ad in the local paper in October and sold 100 of the hens immediately, and could have sold more. The 7½ dozen eggs that I now had to wash each day was more manageable, but soon I realized this was still too many. I put another ad in the paper in December and sold all but a couple of dozen hens, again almost immediately and again I could have sold more. It made me realize that there was a market for ready-to-lay hens all year round here, even though I had been led to believe they were only in demand in the spring. I began raising 300 of them at a time, selling each batch at 18 weeks old as ready-to-lay hens. I tried meat birds a couple of times, but it turned out that selling meat birds was not my strong point, and most of the birds had to go into my own freezer. I decided to stick with the ready-to-lay hens for the most part, having a few experiments on the side with incubating chicks and using a broody hen.
Unfortunately, my allergies to the chicks were becoming unbearable, and I sold the majority of the hens in 2001. I am not so bad with the mature hens, but the chicks give off a phenomenal amount of very fine dust while they are growing. I still have my young rooster and 12 of my "old birds" left, two of which are from my first batch, and the others are from various experiments with broody hens etc. Apart from those 12 old hens and the rooster, I am now left with only the memories, so I decided to share with anyone who has the patience to read this book, that which I had had to learn by trial and error.