Computer software comes in three different flavors: freeware, shareware, and commercial software. Freeware is free to use and does not require any payment from the user. Shareware is also free to use, but typically limits the program's features or the amount of time the software can be used unless the user purchases the software. Commercial software requires payment before it can be used, but includes all the program's features, with no restrictions or time limits.
Commercial software programs typically come in a physical box, which is what you see displayed in retail stores. While it's true that the software boxes are not as big as they used to be, they still contain the software CD or DVD and usually a "getting started" manual along with a registration key used for registering the product. Most commercial software programs ask that the user register the program so the company can keep track of its authorized users. Some commercial software programs, such as newer versions of Microsoft and Adobe programs, require the user to register the programs in order to continue using them after 30 days.
While most commercial software programs are sold in the physical box, many software titles are now available as downloads. These downloads are typically made available from the company's website. The user pays for the program directly on the website and instead of receiving the software in the mail, the user downloads it to his computer. Another popular way of purchasing commercial software online is simply paying for a registration key, which unlocks the features of a shareware program. This upgrades the shareware program to the commercial version, which removes any feature limitations from the shareware version.