iPhone X: What is it and why has Apple decided not to call its flagship product iPhone 8?

There'll be no 7s

New Apple iPhone 6 phones await customers at the Apple Store on the first day of sales of the new phone in Germany on September 19, 2014 in Berlin, Germany (Sean Gallup/Getty Images)

There won't be one new iPhone this year, but three. And none of them will be called what you expect.

Apple is gearing up for its biggest event of the year, and perhaps its biggest ever: the launch of its iPhones. But that preparation has been a little spoiled by a run of leaks that unfortunately detailed a great deal about the new phones.

That includes the naming scheme, which turns out to be one of the more confusing parts of the new products. Apple is likely to explain all this at the event, but for now here's the best explanation of what's going on.

So there's three phones?

Yes: one small, one big, one right in the middle that will be packed with the latest features. Up until now, we'd been referring to those phones as the iPhone 7s, 7s Plus and the iPhone 8, which is a little more clear about what the handsets are.

But then, over the weekend, Apple accidentally leaked the software that will power the new handsets. That shows that Apple will refer to the new phones as the 8, the 8 Plus and the X.

(You can find out all about those huge leaks here.)

What is the iPhone X?

This is the phone you've heard all about: the futuristic, feature-packed, fully-fledged new iPhone. We know a lot about what it will do, and its key features are expected to be a beautiful screen that goes all the way across the front of the phone, and facial recognition technology that means it can be unlocked just by looking at it.

But far more unusual than those features is the branding. The new phone will be known as the iPhone X, marking the first time that a flagship phone has taken a letter, not a number, and going against the general expectation that it would be called the iPhone 8.

Calling an iPhone by a letter isn't actually that rare: Apple brought out the iPhone SE last year, and the second phone was called the iPhone 3G. Perhaps what's more surprising is that Apple didn't go for some of the other options, like calling it Pro in line with its other products or simply dropping the numbering system entirely.

We don't know why they picked the name. It could be something to do with the fact that it will be the tenth anniversary of the iPhone, or just to make what will be a very important and expensive phone sound a bit more exciting.

But the decision not to call it the iPhone 8 is far more likely to be something to do with the less premium versions of the phones. By deciding on two names that aren't directly comparable, the company can make sure that the cheaper one doesn't seem rubbish in comparison.

The name is already causing some controversy, since nobody really knows whether it's pronounced "ex" or "10". Apple has probably decided, but it had a fairly bad track record at making people pronounce "Mac OS X" in the way that it wanted them to.

What's the iPhone 8, then?

This phone could probably be far more reasonably called the iPhone 7s. It will probably be something more like all those "S" models, keeping the same basic outer design but adding new features and upgrades on the inside.

By calling it iPhone 8, Apple is not simply avoiding direct comparisons. It's presumably attempting to signal that this phone is something more than just a refresh year. Whether that's backed up with major new features or is just a marketing decision remains to be seen, since a lot less has leaked about the less premium phone.

Which phone will be more important?

It's the iPhone X that's been getting all the focus in the run-up to the event, and that's likely to continue after it's over. That phone will include all of the latest and greatest features, and be a look at what Apple thinks the handset of the future should look like.

But it will also almost certainly cost more than $1,000, and there reportedly won't be a great deal of them to go around at the time of launch. So while the iPhone X is likely to be the phone that most people talk about, it will actually be the 8 that people buy.

Apple's probably aware of that, and knows that it will be depending on interest in the less exciting of the two phones if it wants to sell a lot of them. That's probably why we got into this complicated situation in the first place: Apple couldn't make or sell enough of the expensive, top level phone and so needed to make a less exciting one, but had to brand the latter in a way that made sure people still actually wanted to buy it.