The original meaning of 'luggage' is 'what has to be lugged about'. Lightweight materials and wheels have made lugging obsolete for sensible travellers these days, but a bewildering choice of containers for all your portable possessions is available. What you buy in the way of luggage and what you put in it obviously depends on how and where you are travelling. If your journey is in one conveyance and you are staying put when you arrive, you can be as eccentric as the Durrell family, who travelled to Corfu with: 'two trunks of books and a briefcase containing his clothes' (Lawrence), and: 'four books on natural history, a butterfly net, a dog and a jam jar full of caterpillars, all in imminent danger of turning into chrysalids' (Gerald, who described this vast logistical exercise in My Family and Other Animals). If, however, you will be constantly on the move and will rarely spend more than one night in any place, your luggage must be easy to pack, transport and carry.

What to take

There are two important considerations to bear in mind when choosing luggage. First, weight is less of a problem than bulk. Travel light if you can, but if you can't, travel small. Second, bring whatever you need to keep you happy. If you can travel, like Laurie Lee, with a tent, a change of clothes, a blanket and a violin or, like some modern travellers, with only a day pack, you will indeed be free. It's perhaps significant that these supremely lightweight travellers usual go solo; you stop noticing your own pong after a few months. Most people, however, are dependent on their customary possessions and must pack accordingly.

Suitcase or backpack?

Your choice of luggage is of the utmost importance and will probably involve making a purchase. Making do with Granny's old suitcase or Uncle John's scouting rucksack may spoil your trip.

Anyone who's had to stand in a crowded Third World bus or the London Underground wearing a backpack will know what an antisocial item of luggage this is. You take up three times more room than normal and every time you turn round you knock someone over. It is no wonder backpackers have a bad name. The trouble is that most modern backpacks are designed for hill-walking rather than travelling. The ergonomic design is superb for distributing weight evenly on your shoulders and hips and the fabric keeps out the rain. Fine for hikers, but if you are a backpacker - in the sense of using public transport and being willing to walk a couple of miles to the bus station - you would do better to go for a combination bag and backpack. Basically, this is a sturdy bag with padded shoulder straps that can be hidden in a special zip compartment when approaching a sensitive border (where backpackers may be given a hard time) or when travelling by plane. Eagle Creek is a good manufacturer of such bags and Rohan now makes luggage as well as clothing. Look out also for a rucksack-cum-bag from Regatta that is designed to allow air to circulate between the pack and your back - ideal for the tropics.

If you are joining an organised group or do not expect to carry your own luggage, you will find a duffel bag the most practical solution. Or two duffel bags since you have two hands. These soft zipped bags are strong and light and can fit into awkward spaces that preclude rigid suitcases. They fit snugly into the bottom of a canoe or the back of a bus and are easily carried by porters or pack animals. When selecting a duffel bag, choose one made from a strong material with a stout zip that can be padlocked to the side or otherwise secured against thieves. If you are looking for a more sophisticated piece of soft luggage, check out the Kiva 'Big Mouth' bag, which, as the name implies, has an especially large opening.

Suppose you are a regular air traveller, what will be the best type of luggage for you? Probably the conventional suitcase and, in that case, you will be well advised - as with most travel purchases - to get the best you can afford, unless you want to replace your 'bargain' luggage after virtually every flight. Cheap materials do not stand up to the airline handling, which usually involves throwing luggage 20 feet onto a hard surface, then allowing it to stand on the tarmac in the rain. For sheer toughness, the traditional hard cases do best. Choose ones made from a strong material such as nylon. These can go up to 1,000 denier. Leather looks smart but is quite heavy. As with all items of luggage, check the zip, which should be strong, and the stitching, which should be even and secure with no gaps or loose threads. Airport carousels can leave black smears on light- coloured items - darker colours stand up to this treatment more happily but are harder to spot among a medley or similar cases. Tie a distinctive ribbon or tag onto the handle for identification.

Few people these days would buy a suitcase that doesn't have wheels. These increase your independence (and save your back). Some wheeled suitcases are far easier to control than others, so check potential purchases out properly in the shop before handing over your money. The classic wheeled suitcase may soon be a thing of the past: the latest design from Kiva uses rollerblades.

Before checking in a backpack or suitcase at the airport, take time to remove all unnecessary appendages (straps, hangers, clips, etc.) and make sure your name and address is both on the label attached to the outside and inside the case as well.

Luggage experts and even those in the airline business often recommend sticking to a carry-on bag if possible. It ensures a speedy exit from the airport and avoids possible damage or loss. In any case, use a carry-on bag for your valuables and anything you can't do without for a few days. To fit under an aeroplane seat, a carry-on bag must measure no more than 45 x 35 x 15 cm.

As well as a carry-on bag, you are allowed the following free items: a handbag (women only - as this is in addition to the carry-on luggage, better take as big a handbag as possible to make the most of your luck), an overcoat, an umbrella or walking stick, a small camera, a pair of binoculars, infant's food for the flight, a carrying basket, an invalid's fully collapsible wheelchair, a pair of crutches, reading material in reasonable quantities and any duty free goods you have acquired since checking in.

Some thought should be given to accessory bags. Everyone ends up with more luggage than they started with, because of presents, local crafts, maps, etc., collected on the way, and a light, foldable nylon bag is very useful. I'm devoted to plastic bags myself and always carry a good supply to separate dirty clothes from clean ones, as well as for those extras.

Security

Choose your luggage with security in mind. Your possessions are at risk in two ways: your bag may be opened and some items removed, or the whole bag may be stolen. Most travellers have been robbed at some time or other, the most frequent occurrence being that small items simply disappear from their luggage. Make sure that your luggage can be locked. With duffel bags, this is no problem - a small padlock will secure the zip to the ring at the base of the handle. Adapt the bag yourself if necessary. Combination locks are more effective than standard padlocks as they are harder to pick. It is harder to lock a backpack, so use your ingenuity. One effective method is to make a strong pack cover with metal rings round the edges, through which can be passed a cable lock to secure the cover round the pack. Luggage may also be slashed, but this treatment is usually reserved for handbags. Apart from buying reinforced steel cases there is little you can do about it. A strong leather strap around a suitcase may help to keep your luggage safe and will be a life saver should the clasps break.

During my travels, I've been robbed of five small bags. I finally learned never to carry something that is easy to run off with unless it is firmly secured to my person. If you keep your most valuable possessions in the centre of a locked, heavy pack or bag they are pretty safe. If you can barely carry your luggage, a thief will have the same problem.

Weight allowances for air travel

On international flights, the IATA tourist and economy class allowance is normally 20 kg, for first class it is 30 kg. For transatlantic flights and some others (e.g. USA to South America), however, you can take far more luggage since the only restriction is to two pieces of luggage no larger than 170 cm. Before you fly, always ask the airline about luggage allowances and ask if the same applies to the home journey. For instance, if you fly Ecuatoriana from Miami to Quito, you will fly down on the two piece system, but will be restricted to 20 kg for your return - a nasty shock for the present-laden tourist.

Packing

Before I go on a long trip I put a large cardboard box into my bedroom and throw in stuff I may need on the trip as I come across it. That, plus a list that is added to as I remember things, makes the build-up to departure relatively unstressful.

Bear in mind that the variable air pressure inside the luggage hold will cause leakage. Shampoos, lotions and other fluids should be in screw-topped tubes or containers. Give the top an extra turn before you pack it. Potentially leaky things such as fountain pens should be carried in your hand luggage. Remember that your Swiss army knife may be classified as an offensive weapon and confiscated.

When packing, put irregular-shaped and heavy items such as shoes at the bottom, remembering where 'bottom' will be when the case is being carried. Clothes crease less if rolled up, or folded round a magazine. Let no space go to waste - fill up shoes with soft or small items such as underwear or jewellery. Top the lot with something large, such as a dressing gown or shawl. Some travellers like to keep their toilet items in different groups, which makes sense when you consider that you do not wash your hair with the same frequency as you wash your face or go out in strong sun. Medicines should be kept in an easily recognised plastic bag. Keep aspirins, etc., in your sponge bag so they can easily be found.

Do not over-pack: if you have to force the lid of your suitcase, you may bend the frame or break the hinges, not to mention what you do to the contents. Better to have plenty of space for those extra purchases. Pad the gaps out with bubble wrap. Then, when everything goes wrong on your holiday, you can relieve the tension by popping the bubbles one by one!