Berlin - If you’re passing through Qatar or have a two-day layover in Moscow, there’s one thing you need to remember to take with you – a transit visa.

As the name suggests, it’s not your ordinary visa and allows you to enter a country temporarily on your way to another place. It's not uncommon for inexperienced travellers to set out on a multi-leg flight without realising that the stopovers may require visas.

A transit visa is generally valid for 24 to 48 hours, and sometimes allows you to be in a country for a couple of days longer.

But there may be limits on where travellers can go during their time in the transit country.

For example, you might only be allowed to stay inside the airport or in a particular town. In Shanghai, for example, there is a transit visa which allows travellers to stay for 144 hours – but only in the city’s metropolitan area.

To be granted a transit visa, you need to show proof that you are continuing your travel to a third destination. Your plane tickets will usually be fine to use for this. If your ultimate destination is a country which requires you to present a visa, you will need to have that with you.

Sometimes you can get a transit visa when you arrive, but often you need to have one before you set off.

And if you’re going to be stopping over, you will need to show your transit visa when you check in at the airport where you start your journey – otherwise you won’t be allowed to travel and your flight will leave without you.