In less than 24 hours, the world will know what Apple's next-generation phone is, if it's a slight upgrade or a major overhaul, if Sprint will become a carrier, and if it indeed features a bigger screen, a better battery, an improved camera, a faster processor, and a voice-activated Assistant.

While many will speculate up until the last second about the features and specifications of Apple's new phone, the fact of the matter is, nobody even knows if Apple is going to release an iPhone 5, or an iPhone 4S, or something in between. Apple has never confirmed nor denied a new iPhone, even though the company promises to talk iPhone.

The following list is a series of facts, not rumors or speculations, surrounding Apple's mystery phone.

Apple is thinking different, again. In the past, San Francisco's Moscone Center has been the building of choice to host Apple's launch events, but not this year. With Jobs out, a new CEO in, and product hype at an all-time high, the company has decided to move the event to Apple headquarters in Cupertino, Calif. Apple likely moved the venue for a couple of reasons: To signify the shift from Jobs to Cook, who will curate Tuesday's event, and to keep all presentation details in-house and secure. Unless the announcement was a big one, secrecy would not be the first priority in choosing the venue, but it seems to be here.

Apple will talk iPhone. Apple's cryptic invitations to the media event were simple but filled with information. Four icons signified the date, time, and location of the event, using the Maps icon to pinpoint Apple HQ as the chosen venue. Most importantly, the invite featured a phone icon with a red number 1; if Apple is offering any clues at all, the invitation may suggest that the company will only unveil one new iPhone instead of two. This notion is further evidenced by the tagline at the bottom of the invitation, which read Let's talk iPhone, mentions a singular iPhone.

This will be the first non-summer iPhone release. Apple's iPhone releases have followed a predictable summer pattern: The first iPhone was released in June 2007, the 3G was released in July 2008, the 3GS debuted in June 2009, and the current model, the iPhone 4, was released in June 2010. This new announcement comes 15 months since the last one, so whatever Apple has up its sleeve Tuesday, the company likely needed those extra three months.

Believe it or not, these three facts are all that is truly known about Apple's iPhone announcement. Everything else is speculation. It's really interesting and potentially exciting speculation, but speculation nonetheless.

Apple has a long history of secrecy; after all, mystery makes things cooler. Apple has a no-tolerance policy for those who leak news tidbits to outsiders, and the company goes to many lengths to throw news media off the scent. For example, it's been said that Apple intentionally spreads disinformation about product plans to its own workers.

I was at the iPod launch, said Edward Eigerman, a former Apple systems engineer. No one that I worked with saw that coming.

Apple's culture of secrecy dates back to its early days. Regis McKenna, a marketing expert from Silicon Valley who advised Apple back then, recalled the introduction of the first Macintosh, when competitors like Microsoft knew about the product before it was officially unveiled.

It really started around trying to keep the surprise aspect to product launches, which can have a lot of power, McKenna said. But what most people don't understand is that Steve [Jobs] has always been very personal about his life. He has always kept things close to the vest since I've known him and only confided in relatively few people.

While many hope the next iPhone is everything everyone ever dreamed it would be, one thing is certain: everything will finally be known when Apple CEO Tim Cook takes the stage in Cupertino on Tuesday, Oct 4, at 10 a.m. PDT.

Apple has sold more than 110 million iPhones around the world.