Some people may not be able or willing to spend much money, but wish to see the world anyhow. This means they should either keep their expenses low or earn money while travelling.
Mode of travel
You can keep a check on your expenses by opting for a minimum budget. Many cities are quite compact and can be seen by walking. After all, exploring a city on foot has a different charm altogether. Cycling can be a good and cheap way to explore areas a little further apart than what you can see by walking. Some cities have cheap bicycle hire schemes run by urban governments.
However, in some countries like the USA or Australia, bicycle hire for two people can easily cost more than a car hire for the same period, and the market for second hand bicycles can take time to sell into. For an extended trip it will be much cheaper to buy a used bike rather than rent.
Used bikes can usually be purchased for reasonable prices at thrift shops, pawn shops, and garage sales.
Also, travel insurance which usually covers rental car damage or excess payable usually does not cover loss or damage to a bicycle you may hire. Besides you can also opt for hitchhiking, which is faster and normally just as cheap.
Use mass public transport instead of taxis or other faster, more expensive means of transportation. For public transport, look into multi-use tickets. Many systems have tickets that can be used a certain number of times, or over a certain time period, for a considerable discount over buying each ticket individually.
One should also check for eligibility of discounts like Western Europe frequently has blanket discount schemes for people under 26, Great Britain has a youth discount card that you can buy and which pays for itself after three or four journeys (a 'Young Person's Rail Card'), and many countries have discount schemes for students, pensioners and sometimes disabled people.
Local transport is often considerably cheaper than express or long distance transport. In European countries in the outskirts of cities public transport system can often overlap with a neighbouring city, often providing a cheaper method of transport than an inter-city trip. In countries like Japan, local trains are cheaper if you have time on your hands and can manage the connections.
Camping is an obvious choice for cheap accommodation, and it's often the closest accommodation to lots of natural attractions. However, this may mean burdening yourself with camping equipment and even protecting yourself from the weather.
Also consider using a tent or hammock that blends well with area vegetation, green is best for most areas.
You can also opt for sleeping in your car. Although illegal in many areas, if you have a van style vehicle with limited rear windows, it is often easy to get away with.
A budget traveler can also opt for hostels or guesthouses, usually the cheapest type of commercial tourist accommodation. Many hostels offer cheap one-to-four-person rooms, but the cheapest of all are dorms shared by up to twenty people: you'll usually be given a key to the room and left to choose a bunk bed.
The cheapest places to buy food are traditional markets, supermarkets and street vendors. Some cities have cheap restaurants in squats, usually selling vegetarian or vegan food for the price of the ingredients. Some countries also have heavily-subsidised university restaurants, sometimes open to foreign students as well.
Self catering, buying your own ingredients and preparing your own meals, is a great way to stay on a budget. Many hostels provide kitchens where you can cook your meals.For restaurants, avoid eating in the main tourist thoroughfares. If you get into the side streets and back alleys, you'll find cheaper restaurants that often serve tastier, more authentic meals.