What luggage features prevent theft?

No luggage is impossible to steal or steal from but anything that makes it more difficult will reduce the probability of theft.

There are generally two things you need to worry about:

• Theft of your luggage.
• Theft of some or all of its contents.

The best way to avoid theft of your luggage is to keep in under watch you trust. That is why, most of the time I leave luggage in a locked locker with people or cameras watching. Hotels around the world usually offer this as a service. If you are staying at a rental other property though, is is less likely that this is offered.

The other way to prevent luggage theft is to tie it securely to a fixture or other difficult to move object such as pipes, railings or furniture. There are a number of companies that sell devices purposely for this. Think of it as a bike chain and lock for your luggage.

Should the luggage not be under watch by a trusted person or service, you need to worry about getting it broken into. Anything with soft-sides - unless reinforced by Exomesh - is already vulnerable since it can be cut to bypass any lock or closing mechanism. Anything with a zipper is also easily broken into since all you need is a ballpoint pen to open it. Watch this video to see how easily it can be done and undectetable it is after the fact.

The above video makes it clear that what is really a hard-sided suitcase with built-in locking hash so that you can use your own sturdy and hard to pick lock. The video goes through many examples and shows which locks are the most difficult to break into. Incidentally, just a few days after seeing this video, I saw a man with exactly this type of case with two enormous locks going through it.

Avoid hard-suitcases with built-in locks as these are usually TSA ones and offer minimal protection since they are easy to break, quick to pick and master keys are not that hard to make. Here's a video of a guy opening them in seconds.

Pacsafe makes products designed to address both issues. The one I use is a 85L Bag & Backpack Protector which provides some security against both luggage theft and theft of the contents. This is designed to protect backpacks by encasing them into a metal mesh which makes it hard to cut into the backpack, plus a metal tether to attach the whole thing to a fixture. The metal itself is rather thin and lock is not top-grade either, so this provides far less protection getting a hard suitecase with your own sturdy lock and using a bike-chain to fix it but the whole thing is relatively light and weighs just over a pound (0.52kg). This kind of thing - I don't know if there are others actually - is a good deterent in making your luggage a little harder to steal and steal from than most.

Pacsafe also makes lugggage with Exomesh built in, so you only have to add a tether of chain in order to secure it. Again, it would not be very difficult to break into or cut the chain but it means that tools are needed to steal it.

(I originally wrote this as a comment, but I think it is important enough to merit an answer. It's not in any of the other answers)

For a laptop, regardless of where and how you hide/store it: make sure it is fully powered off/in sleep mode when not in use. You don't want it broadcasting Where's the Wifi? or Can we connect over Bluetooth? while it's left unattended.

Luckily, most laptops go into sleep immediately when you close the lid, and if they don't you can usually see some lights still on (or you hear the disk spinning). So check yours before taking your trip.
(And confirm that when it comes out of hibernation, it asks for your login again).

Notes: some people claim that even in sleep mode there are still detectable signals, but that's not true - e.g. there was such a claim in 2010 by security company Credant Technologies [1],[2],[3])

I can only speak to traveling inside the US. I don't know if it will apply to you.

You have four concerns to measure against.

1. Theft of the luggage
2. Theft of the stuff in the luggage
3. Ease of use
4. Legal requirements/needs/etc.

So the awesome thing about luggage to thieves is that it's already portable. It comes with wheels and handles and straps. Better yet, all you have to do is pick it up. You don't even have to slow down. Who cares what's in it. Maybe it's good maybe is just dirty boxers, the risk is so low it's worth rolling the dice.

1. To combat this, your best bet is to use wearable luggage, a strap/leash to connect it to you, or a lock that keeps it in place. A backpack is a good example of wearable luggage. Keep in mind that wearable luggage only works of you wear it. The second you set down your backpack, it becomes a good target again. This works for money belts, "fanny packs" etc etc. You could alternatively use a cable lock to attach your luggage to a post or sign. Keep in mind that this has some serious legal side effects if your going to walk away and leave your luggage. (more on that later)

2. Don't let the ads fool you, there's not going to be a lot of people walking up to your luggage, and trying to use a blow torch, or jig saw to get in. You need something that will keep out a pocket knife, and will stay closed. For example a back pack on a subway is easy to get into. Till you put those little locks on the zippers. Then it's better to just move on. Maybe while your shopping or asleep someone will try to cut through your pack to get the goodies, but honestly, if there bringing a knife it's more likely there just going to tell you to open the pack. Good knife resistant luggage is all it takes. That can be soft sided or hard, doesn't matter much. Remember, if they want to steal your luggage, there just going to walk off with it, and worry about opening it later.

3. So I wanted to include this one because you need to make sure your choice in luggage is easy to use. For example a back pack will have to be gotten into at odd times. You don't want to be the guy in the store that needs to get into his back pack to get that one piece of paper and has to empty the entire thing on the counter top. Try to make sure that your security choices are balanced with ease of use. After all a travel safe would be best, but who wants to lug around a 2 tonne safe to the store.
4. Lastly there are some rules/laws/etc that you need to be aware of. For example TSA approved locks for flying. Or the fact that you can't leave your luggage chained to a pole while you go into a shop. (Unless you want to see the bomb squad explode your underwear.) Make sure you look into, and account for that.

Two things are most important in all of this.

Do not leave your luggage unattended. Keep an eye on it at all times.

People that steal luggage are in for an easy score. Don't be an easy score.

A hard-sided case more secure than soft cases? In hostel? Seriously? They are literally screaming 'steal me, I have something valuable within'!

The features that will make your luggage less likely to be even considered to be stolen are:

• cheap
• weared off
• dirty
• stinky
• full with crap

A cheap rucksack, with some holes, dirty, full with used clothes is quite likely to be the last item to be inspected by potential thief. Worn socks have even power of deter toll officers (through the dogs won't give up so easily).

If you are in a poorly secured hostel and you have to leave your stuff behind there, put your laptop and other valuable items in a big hard case suitcase (say 300 liters volume) that can be very securely locked. Then put a large number of bottles of water in there, you may also put a sack filled with stones in the suitcase. Fill it until it weighs well over 150 kg. Then lock your suitcase. The huge weight of your suitcase will make it impossible for thieves to quickly sneak into your room and carry it away without catching attention. Also they can't use knives to cut it open quickly to get the access to the valuable items. When encountering your suitcase, a thieve will decide to skip your room and check out another room.

To be able to do this, you should bring the large suitcase filled with a few hundred empty water bottles with you, so this may come at the expense of having to check in one piece of luggage.