Keeping kids comfortable in the outdoors is the key to happiness (yours and theirs). When it comes to choosing the right clothes, start next to the skin. The first or inner layer keeps your child's skin dry and comfortable. Lightweight cotton t-shirts and shorts work well in summer months.

Although it’s comfortable and breathable in hot weather, cotton absorbs and retains water. This makes it difficult to dry. Wet kids are soon uncomfortable in the cold. Avoid heavy cotton clothing in the outdoors whenever possible.

Synthetic fabrics, such as polypropylene, help move moisture away from the skin -- a process known as wicking. Long underwear pieces made of these types of fabrics are good inner layers in cooler months.

Next, add a layer of protection and light insulation. Long-sleeved shirts and pants provide shade from the sun in summer months and warmth for spring, fall, and winter. The middle layer can be lightweight, but should cover exposed arms and legs.

If it's really cold, turn up the heat with a thick woolly sweater or comfy pile jacket and pile pants. Both wool and pile stay warm even when wet and pile has the extra benefit of drying quickly.

When wind and rain are a concern, break the elements with a shell layer. Combat wind with a nylon shell. Coated nylon works well for raingear. Waterproof, breathable fabrics are also available as weather-busting shells. If cost is a factor, remember that kids sweat 40% less than adults, so breathable fabrics may not be necessary. Any good shell though, should have an attached hood that covers all of the head.

When your child is young (0-3 years), they are active only in short spurts, if at all. They will be spending downtime being carried and need to be dressed warmly. One-piece outfits are great for this; there are no gaps to allow the weather in. The downside comes when changing diapers and stopping for potty breaks. Once your child is hiking alone though, multi-piece outfits are the only way go.

Now it's time to put the whole system together. Add or subtract pieces depending on the weather. If it's hot, keep it simple with shorts or loose, light clothing. Add a layer if the temperature drops. If the wind blows, break it. If it rains, bust it with a waterproof shell (top and pants).

And don't forget about headwear, over 50% of heat is lost through the head. If your child's toes are cold, put a hat on them. Wide brims help keep moisture and sun away from the face.

Desert hiking, mountain trekking, coastal backpacking -- let your children experience it all, in comfort, thanks to the simple concept of layering. One - inner comfort layer, two - warmth layer and three - shell layer.

See for yourself, it's as easy as 1-2-3.