Alongside the iPhone, undoubtedly the biggest smartphone release of any given year since the turn of the decade has been the latest Samsung Galaxy S.

This year it's the turn of the Samsung Galaxy S8, and the South Korean tech giant has an awful lot riding on it.

Tonight's the night that Samsung plays its hand for 2017. Here's everything you need to know about the Samsung Galaxy S8 launch.

When is the Samsung Galaxy S8 being announced?

Samsung is holding two simultaneous Unpacked events (which is how it refers to all of its phone release shindigs these days) at London's Olympic Park and New York's Lincoln Center.

These will take place at 4pm London time and 11am New York time.

These are press-only events, but Samsung will be live-streaming them. Just point your web browser here at the appropriate time.

Why is the Galaxy S8 so important for Samsung?

While the Galaxy S7 was one of the best phones of 2016, the subsequent Galaxy Note 7 was a bit of a PR disaster for the company. Its too-tightly-packed-in battery started exploding on people, forcing Samsung to issue a humiliating (and costly) recall.

The result is that while Samsung had a pretty good year financially (thanks to the Galaxy S7), its reputation took a hefty dink. It's imperative that the company hits the ground running with its next major smartphone release, and that will be the Galaxy S8.

In addition, there's the looming spectre of Apple, which is widely expected to issue a completely new iPhone design this autumn. The iPhone 8 could be the company's most radical phone yet, so Samsung really needs to make an impact with its own 2017 flagship.

What can we expect from the Galaxy S8's design?

The main departure from Samsung's previous phones will be the composition of the front of the device. Several leaks (including the below image from reliable tipster Evan Blass) have revealed that the device will drop the physical home button and dramatically reduce the size of the bezels - that's the margins around the display.

The result will be a phone that's almost (but not quite) all screen. Or rather, TWO phones - there'll be a 5.8 inch and a 6.2 inch 'Plus' model. Meanwhile, the aspect ratio for both displays will apparently be an elongated 18.5:9 rather than the usual 16:9.

Samsung's also set to ditch the classic Galaxy S form factor altogether in favour of a wholesale embracing of its premium Edge design. This means that the screen will taper off at the left and right edges.

And yes - these huge screens (along with the inevitable power boost) should make the Galaxy S8 a truly awesome gaming phone.

Any other hardware tricks?

That revamped front will mean that the Galaxy S8's fingerprint sensor gets repositioned to the back of the phone, alongside the camera. This could take some getting used to for established Galaxy S (not to mention iPhone) fans, though it's far from unusual among Android phones in general.

It also seems that Samsung is going to resist going the iPhone route and will keep the headphone jack around for another year at least. Good call, we say.

More recent leaks suggest that the Galaxy S8 will be able to output audio to two distinct Bluetooth devices simultaneously, which would make it quite the impromptu party-in-the-park device if nothing else.

Oh, and the Galaxy S8 will almost certainly have a better camera than the Galaxy S7 - which means we'd put money on it becoming the best cameraphone on the market, at least until September. You know what happens then.

What about software?

While Samsung has largely aced the hardware side of things (ignoring the Galaxy Note 7) in recent years, its software continues to be a source of contention. Still, you can bet that it will continue trying to differentiate its phones through its TouchWiz UI.

It'll be interesting to see how the company utilises all that extra screen space, but that's not going to be the most interesting software feature of the Galaxy S8.

That honour will surely be split between Bixby, the company's new voice-activated assistant, and a new DeX desktop function that will let you dock the Galaxy S8 and use it as a PC (with an additional keyboard, mouse and monitor of course).

This idea hasn't amounted to much in the world of Windows 10. What makes Samsung think it can do better? Tune in at 4pm/11am to find out.