The big day has finally come: Apple’s iPhone 7 is launching worldwide.

After months of waiting and rampant speculation over what Apple AAPL would announce, the iPhone 7 is hitting store shelves. And for the big event, Fortune has compiled the following guide on everything people should know before they get ready to head down to store shelves in hope of getting their hands on Apple’s latest headset. Truth be told, it might be tough, if not impossible, to get the iPhone 7 if you’re not already reading this from a line at an Apple store. But with the right persistence and a little luck, you might just find one to buy.

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What is the iPhone 7, anyway? OK, in case you missed Apple’s big press event last week, let’s recap. The iPhone 7 is Apple’s latest-generation smartphone, featuring a slightly modified design, a dramatically improved camera design, and a new jet-black color that, while gorgeous, could suffer some “micro-abrasions,” or small scratches, according to Apple. The iPhone 7 is also the most powerful iPhone yet, featuring Apple’s A10 processor, which should load apps quickly and handle any graphics-heavy game without trouble. The iPhone 7 is running Apple’s iOS 10, which launched earlier this week, and comes in a 4.7-inch variety called the iPhone 7, as well as a 5.5-inch model known as the iPhone 7 Plus. Oh, and there’s no headphone jack.

No headphone jack? What do you mean? Yes, the iPhone 7 is the first iPhone from Apple not to come with a headphone jack. Instead, the iPhone 7 comes with an adapter that will allow users to plug in their wired headphones through the smartphone’s Lightning port. Apple announced new AirPods at its press event last week, which are wireless headphones designed to connect to the iPhone 7 and Apple Watch. They’ll launch late next month for $159. You can also buy just about any other wireless headphone on the market and connect it to the iPhone 7 via Bluetooth.

What have people said about the iPhone 7 so far? Some media outlets, including TIME, which is owned by Time Inc., the company that publishes Fortune, have gotten their hands on Apple’s newest smartphone. In general, the reviews are positive, with many saying the lack of a headphone jack isn’t such a big deal. Others have complained a bit about the lack of a major upgrade, but at least so far, folks are saying the iPhone 7 is a worthy buy.

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Should I buy the iPhone 7 or iPhone 7 Plus? Ultimately, deciding whether to buy the iPhone 7 or iPhone 7 Plus comes down to whether you want a big device. As mentioned, the iPhone 7 Plus is big, with a 5.5-inch screen, and comes with a dual-lens camera instead of the single-lens camera on the iPhone 7. The iPhone 7 is a bit more manageable, thanks to its 4.7-inch screen, but doesn’t have the better camera. While I generally prefer the iPhone 7 Plus (a big screen is nice), Apple said on Thursday that it’s run out of its initial supply of iPhone 7 Plus units. So if you’re hoping to buy one today, you’ll be out of luck.

How much does the iPhone 7 line cost, anyway? Oh, what a tricky question. The easy answer is to say that the unlocked version of Apple’s new iPhone 7 starts at $649, while the iPhone 7 Plus starts at $769. However, Apple and its carrier partners are all offering monthly installment options that defray the smartphone’s cost over a couple of years, and prices there can range, depending on the carrier you choose. Here’s a handy guide on weaving through the myriad of iPhone 7 options.

OK, I want one. Where do I get it? Unfortunately, you might be out of luck if you want to get an iPhone 7 this morning. Apple and its carrier and retail partners started offering preorders on the iPhone 7 last week and their stock quickly ran out. Many who tried preordering the smartphones just hours after launch saw their shipment dates pushed back as far as November for the jet-black version. Now, dates have been pushed even farther. The only real option, then, is to stand in line at a local carrier or Apple store in hopes of getting one of the few devices they might have in stock. However, if you’re not already standing in line, you might be out of luck: Some would-be iPhone owners started lining up last night.

If I can’t get one today, what can I do? Unfortunately, getting an iPhone 7 today might be difficult. And since supply is so limited, you might need to wait weeks or even months before you get the version you want. If you don’t get an iPhone 7 or you think your chances are slim, at best, try ordering one on Apple’s site or on your carrier’s website. You’ll need to wait to have it shipped to your house, but at least you’re on a list. Also remember to keep calling your local Apple store. Chances are, Apple stores will get a trickle of supply, and if you catch it at the right time, you might be in luck in the coming weeks.

Good luck!