Heading to London and need to get around the city while you're there? Get hold of an Oyster card for the Tube, buses, the DLR (Docklands Light Railway) -- and it's also accepted in some cafés and newsagents for small-value purchases.

In true British fashion, the rules and regulations are a bit complicated -- so here's our guide to getting and using an Oyster card in London.

What is it and where can I use it?

Oyster is a contactless smart card from TfL (Transport for London) that uses an RFID chip when you touch it to the yellow reader at the gates on Tube/DLR platforms or on the bus. (No, we have no idea why it's called Oyster either.)

Money is stored on it and the account is debited according to the number of zones that you have travelled through when you touch out of the Tube/DLR. On the bus, your Oyster card is debited when you touch in -- there's no need to touch out, since there's no zone network on the buses.

You need to touch in and out every time you use the Tube and DLR (Docklands Light Railway, which goes out to the financial centre in Canary Wharf and to London City Airport). If you don't, you'll be charged the maximum possible fare of £7.40 -- and that doesn't count towards your daily price cap either. 

Forgetting to touch out is a classic rookie mistake, especially on the DLR in the Docklands financial district, where there are fewer platform gates. Unfortunately, it's a mistake that'll cost you the equivalent of A$12.

How and where do I buy an Oyster card?

Oyster cards are for sale at all Tube stations, including at Heathrow Airport Tube stations. Be warned that there are often queues at the Heathrow Tube stations.

The card itself is a refundable £5 deposit, plus £2 minimum fare. A maximum of £90 of prepay money can be loaded onto a card. There are coin operated Oyster dispensers in Heathrow if you have a stack of pound coins. 

Automated machines that take credit cards and cash are available to top up your Oyster account. However, if you don't have a chip-and-PIN card that your Australian bank has confirmed will work in the UK, you may have to talk to a real live human being in the ticket office unless you have enough cash on you. Most major Tube stations still have staffed ticket offices.

You can also purchase an Oyster card online from the British tourist board and have it posted to you in Australia -- although at A$21 for a £10 card, $37 for £20 or $53 for £30, this doesn't sound like a bargain.

How much are fares?

You'll probably want to refer to the Tube map for the travel zones to make sense.

First off, don't forget that you can't use Oyster on the Heathrow Express or Heathrow Connect trains from Heathrow to Paddington station. 

There's an exceedingly dense and somewhat confusing fares page on the TfL website, but here's a selection of common Tube journeys for business travellers.

Assuming you're arriving at Heathrow, the initial fare to central London Zone 1 from LHR (zone 6) is £4.50 with Oyster before 0930 or £2.70 afterwards. The equivalent cash fare is £5. 

One Tube journey within zone 1 costs £1.90 no matter what time you travel. The equivalent cash fare is a comparatively whopping £4.

Oyster has a daily price cap. For Tube Zones 1+2, it's £8.00 including peak (before 0930) and £6.60 offpeak-only. There's no saving against the comparable Day Anytime Travelcard and Day Offpeak Travelcard, but you are likely to save time buying a ticket if you preload.

You can also use Oyster on London buses -- and, despite their often confusing routes, they're an excellent way to see the city and faster than Tubes on some journeys. The Oyster fare is £1.30 per journey, with a £4 daily price cap. An equivalent single cash bus fare is £2.20, but be aware that there are some buses that don't accept cash. (There will usually be a sign and a ticket machine near stops where this is the case, but not always. Another benefit to Oyster.)

Should I register my Oyster card?

You don't need to register your Oyster if you just want to put pre-paid money on it, or if you want a weekly ticket. Registering can be useful if you're the sort to lose your card, though -- you can quickly nip online, cancel it and get your money back.

You'll need to register your Oyster card if you want to load it with monthly ticket: those are only usually worth it if you'll make more than three trips a day all week. Registering involves either filling out a form at a ticket office (hey, it's the UK, of course it involves a form), or there's an online option.

How do I get my money back off my Oyster card?

At the end of your trip, you'll probably have some money left on your Oyster. If you're planning a return journey to London, keep hold of it for next time! If not, then you'll probably want to get your money back -- including the £3 of the deposit.

Simply hand it back at a ticket office (probably the one at Heathrow) and your money will be refunded -- in cash. Don't forget to leave some time for this, since the Heathrow Tube stations are notorious for delays at seemingly random times of day.

So what about using my Oyster card on National Rail trains instead of the Tube?

Oyster can be used on some National Rail trains in London and nearby areas, including the double-orange-lined London Overground branded services on the map.

However, the rules and regs are even more complicated for these journeys, and most business travellers won't need to use these trains anyway. For full details, check out TfL's page on using Oyster on National Rail.