Just about every traveler has seen cards in hotel rooms and ship cabins advising that the management practices conservation. Guests are invited to save resources by skipping a day or two of towel and linen-change service. This is the extent of what most of us know about sustainable travel, a flourishing concept adopted by the hospitality and travel industry to sustain business without negatively affecting the earth or its people.

Everyone can travel responsibly, conserve natural resources, support local cultures, and leave behind only footprints. Following are steps, big and small, that can make a difference to our planet, this best of all possible worlds.

Practice your environmental ethic: Don't waste water and electricity when you travel even though you won't receive a bill for excess use. Remind yourself that 75 percent of the energy in a hotel room is used when the bathroom lights are left on for more than two hours.

Disconnect home/office appliances: As much as 10 percent of the electricity used at home and work is wasted energy burned by unused gadgets and equipment. Unplug any appliance unused while you're away such as computers, printers, chargers, televisions, video game players and microwaves.

Pack lightly: Plan ahead to take only the minimal amount of mix-and-match clothing for all anticipated occasions and destinations. Consider that every 10 pounds of luggage per traveler requires an additional 350 million gallons of jet fuel per year.

Travel paperless: E-tickets have changed not only our travel habits but also reduced resource waste. According to the International Air Transport Association, the switch from ticket coupons to e-ticketing saves the equivalent of 50,000 mature trees each year or about three square miles of forest.

Choose responsible tour and hotel operators: Select among the growing number of companies that practice sustainable travel through their booking and operating policies. Before you make a reservation, ask about any environmental certifications such as Green Globe, the international benchmarking and certification system for the travel and tourism industry.

Sleep simple: Stay in the smallest, newest, most pared down hotel that meets your standard of comfort. Luxury hotels, by the nature of their services, consume a lot more energy and other resources than simpler properties.

Bring your own water bottle: More than 60 million plastic water bottles are thrown away in the United States each day. Recycling or reusing those bottles instead would save enough energy to power a 60-watt light bulb for an entire day in 15 million households. While traveling, use a portable filtered water bottle or a reusable filter designed to fit in standard sport and water bottles.

Pack a battery charger and power converter: Rechargeable batteries reduce toxic waste. Regular dry-cell batteries containing lead, cadmium, nickel, and other heavy metals improperly dumped in landfills can contaminate the air, ground, and water.

Select the right gear: Choose environmentally friendly clothing and travel gear made from recycled, reused, organic, and sustainable natural materials such as cotton, hemp and bamboo.

Pack a reusable shopping bag: Use a basic canvas tote or similar sturdy, washable bag to carry souvenirs and other purchases made during your trip. Americans toss out some 100 billion nonbiodegradable plastic bags each year, and the ones that don't end up in landfills, litter roadways and float in waterways, where they can choke or entangle wildlife, which mistake the bags for food.

Buy from local artisans: Support and celebrate local cultures by purchasing original handicrafts directly from the artisan whenever possible. Travelers' economic decisions directly affect the survival of fragile indigenous cultures.

Don't buy endangered artifacts: Find up-to-date information on which animal and plant species are considered endangered around the globe by consulting the Convention on International Trade in Endangered Species.

Go wild: Book a safari or eco-adventure. Sustainable tourism is the last great hope for protecting rare and endangered plant and animal species and their vanishing habitat.

Stay on the trail: According to the Sierra Club, veering off the marked route in the wilderness can damage the integrity of archaeological artifacts, erode or compact soil, degrade animal habitats and water quality, destroy wildflowers and vegetation, spread invasive weeds, and harm animals.

Give back: Show your appreciation in a practical way — pick up trash, donate school supplies, consider volunteer vacations. National Geographic sponsors The Green Guide Web site for everyday living, including travel, at www.thegreenguide.com.