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A BTO vulnerability is a flaw in a copy protection scheme such that a "cracked" copy of the product &mdash; that is, a copy that has been modified to defeat the copy protection scheme &mdash; is Better Than the Original (i.e. an official copy) in some way.

Some opponents of copy protection have argued that all copy protection schemes, by definition, include BTO vulnerabilities to some degree, and that publishers who utilize copy protection are thereby creating incentives for customers to obtain cracked versions of the products rather than purchasing them.

"Type word 4 on page 6 of the manual"

In the 1980s and early 1990s, many pieces of computer game software would halt the game after a few minutes and ask the user to look up and type in a certain word within the product manual, or look up a word or symbol on some other piece of product packaging. An incorrect answer would usually cause the game to simply quit. The theory was that users with an original, purchased copy of the software would not be very inconvenienced by this, whereas copyright infringers who obtained the game over the BBS network would not have the manual, would answer the question incorrectly, and would not be able to play; this would, the theory went on, provide an incentive for the illegal users to go purchase the game.

A "cracked" version of such software had two advantages over the original version:

Users did not have to go through the inconvenience of looking up something in the manual every time they wanted to play the game.

If the manual was lost, a cracked version of the game would still be playable.

Music CDs made unreadable on PCs

After the popularity of music sharing on Napster exploded in 2000, several music publishers embarked on projects to publish some or all of their music on non-standard, intentionally corrupted audio CDs which are intended to play correctly on consumer CD players, but which are intended to cause problems if played in a computer CD-ROM drive. These problems ranged from producing silence or white noise to causing a computer failure.

An extreme example of bad behavior by an original CD, ensuring that cracked copies were BTO, was the "Sony rootkit" scheme that caused a brief furor in 2005 when it found that the copy protection software surreptitiously installed itself on the user's computer and seized control of certain aspects of the system.

Opponents of such measures allege that instead of purchasing CDs that include copy protection of this kind, some people who want to play the CD on their computer instead obtain the equivalent mp3 files from Internet file-sharing networks, or even purchase a standards-adherent copied CD from another consumer.

This list shows which CDs in the UK have been identified as intentionally corrupted.

"Please insert the game CD and press OK"

Some computer software, particularly computer games, require that the program's original CD be in the CD-ROM drive for the program to function. If the original CD is not detected, the software halts operation and displays a dialog box asking the user to insert the original game CD and try again.

Some software with this sort of copy protection does this in order to store bulky files on the CD-ROM in order to avoid consuming space on the user's hard disk; this was particularly popular in the early 1990s when large media files started to appear in CD-ROM computer games, at a time when consumer hard disks were measured in the tens of megabytes. Today, however, consumer hard disks are much larger than even a DVD-ROM disc, and the requirement that the CD be present is purely for copy protection.

Cracked software circumvents the CD requirement, providing several user benefits:

The user no longer has the inconvenience of having to find the CD-ROM and tie up the CD-ROM drive.

If the CD is lost or damaged, the program is still usable.

On laptop computers, battery life is extended because the CD-ROM drive motor is never spun up.

The program starts loading immediately (without asking for a CD), and several seconds are saved by not having to spin up the CD-ROM drive motor and read data from the CD-ROM.

Online activation

Online activation is a scheme that requires a user to contact the software vendor with a valid serial number (and usually also their contact details) before they can use the product. Some software allows itself to be used for a while &mdash; 30 days, or 50 uses, perhaps &mdash; before activation is required.

Cracked versions of this sort of software includes several benefits for the user:

Does not require the user to have Internet (or in some cases, phone) access.

Privacy is maximized by not transmitting the user's details to the software vendor.

Software can be used immediately after installation, without having to spend time making a phone call or filling out an Internet form

The software keeps working even if the servers go offline (for instance, if the company goes bankrupt; see for instance DIVX).