The serial numbers of Apple products contain a codified language that can give you information about your Apple device that can’t be found through any other means—everything from the location where it was manufactured, the date it was manufactured, and much more. This information can be valuable for troubleshooting issues with your device or just for curiosity’s sake. So let’s get to breaking down their impenetrable code.

The most straight forward way to decode your serial number is to type it in to an online service. Your Apple device’s serial number can be found either in the device’s settings menu or printed on the device. One online service can be found on Apple’s official website, and can help you determine the model of your device, whether it has a valid purchase date, and whether it’s still covered by Apple’s technical support. Apple’s own serial number lookup barely scratches the surface though, leaving most of the info it contains out of their results.

The Apple Serial Number Search tool developed by the cryptanalysts here at Beetstech can help you to uncover a whole lot more info about your Apple device. This tool not only lets you look up Apple devices by serial number, but it returns all compatible parts, and even allows searching by other criteria like EMC number, model identifier, and model number. Additionally, this tool lets you find Apple parts by searching the Apple Part Number, a part number printed on the component, or any combination of keywords you can think of.

But today we’re breaking it down the old fashioned way, and while not everything can be determined through this method, the serial numbers of Apple products follow a structure that allows you to figure out some information with the naked eye. Apple devices manufactured after 2010 generally have 12-character alphanumeric serial numbers, with the first three digits representing the manufacturing location, the following two indicating the year and week of manufacture, the next three digits providing a unique identifier, and the last four digits representing the model number.

Each manufacturing location is represented at the start of the serial number by a different alphanumeric code. Apple manufactures their devices in a variety of locations, and unfortunately not not all location codes are known, but the following is a mostly complete list of codes and their corresponding factories:

The year and week of manufacture are also represented by an alphanumeric code which is, fortunately, easier to decipher. The fourth character of the serial number represents both the year the device was manufactured in, and whether the device was manufactured in the first or second half of the year. The following table shows how to interpret the fourth character:

The fifth character represent the week in which the device was manufactured. There are 28 possible characters in this spot: the digits 1-9 are used to represent the first through ninth weeks, and the characters C through Y, excluding the vowels A, E, I, O, and U, and the letter S, represent the tenth through twenty-seventh weeks. For devices manufactured in the second half of the year, add 26 to the number represented by the fifth character of the serial number. For example, a product with a serial number whose fourth and fifth digits are “JH” was manufactured in the 40th week of 2012.

The next three digits are an identifier code which serves to differentiate each Apple device of the same model which is manufactured in the same location and during the same week of the same year, ensuring that each device has a different serial number. Finally, the last four digits of the serial number represent the product’s model.

The serial numbers for iPhones additionally contain information about the device’s color and storage capacity. For iPhones manufactured after 2010, this information is coded in the final four digits of the serial number; the ninth, tenth, and eleventh characters represent the iPhone’s model and color, and the final character represents the iPhone’s storage capacity.

Decoding the serial numbers of Apple products can be useful for a number of reasons. If you are interested in repairing your device yourself, determining which factory the device was manufactured in, or the date of manufacture, can help you to determine which replacement parts must be ordered to fix the device. Additionally, understanding the serial number structure can help you to troubleshoot issues with your device, as known issues can arise on products manufactured in certain factories or on certain dates.