Windows Vista Update

A serial number is a unique number that is one of a series assigned for identification which varies from its successor or predecessor by a fixed discrete integer value. Common usage has expanded the term to refer to any unique alphanumeric identifier for one of a large set of objects, however in data processing and allied fields in computer science. Not every numerical identifier is a serial number; identifying numbers which are not serial numbers are sometimes called nominal numbers.

Sequence numbers are almost always non-negative, and typically start at zero or one.

Serial numbers are valuable in quality control, as once a defect is found in the production of a particular batch of product, the serial number will quickly identify which units are affected. Serial numbers are also used as a deterrent against theft and counterfeit products in that serial numbers can be recorded, and stolen or otherwise irregular goods can be identified.

Many computer programs come with serial numbers, often called "CD keys," and the installers often require the user to enter a valid serial number to continue. These numbers are verified using a certain algorithm to avoid usage of counterfeit keys.

Serial numbers also help track down counterfeit currency, because in some countries each banknote has a unique serial number.

The ISSN or International Standard Serial Number seen on magazines and other periodicals, an equivalent to the ISBN applied to books, is serially assigned but takes its name from the library science use of serial to mean a periodical.

Certificates and Certificate Authorities (CA) are necessary for widespread use of cryptography. These depend on applying mathematically rigorous serial numbers and serial number arithmetic

The term "serial number" is also used in military formations as an alternative to the expression "service number".

A software license is a license that grants permission to do things with computer software. The usual goal is to authorize activities which are prohibited by default by copyright law, patent law, trademark law and any other intellectual property right. The reason for the license, essentially, is that virtually all intellectual property laws were enacted to encourage disclosure of the intellectual property. As software is so easily replicated, disclosure is not an option that most software vendors would prefer to avail themselves to. The result is that the vendors need an alternate method of allowing the licensed user to use the product but still be restricted so as to prevent certain reverse engineering rights the user might otherwise have as a result of the default intellectual property rights.

Typically, then, the software license is a complex document, identifying the specific usage rights that are granted to the licensee, while also stating the license limitations. For example, a software license might give permission to allow a certain number of concurrent users of the software. This means that at any given point in time, a limit exists on the number of people who can use the software. As a specific user stops using the program, then another, different user can start to use the program. Compare and contrast this with a named user model, whereby the software is licensed to specific individuals. Regardless of whether the named individual is actually using the product or not, another individual is not licensed to use that same copy of the software.

A software vendor may offer a software license unilaterally (without giving the licensee the opportunity to negotiate for more favorable terms), or even as part of a software license agreement with another party. Virtually all proprietary software is sold under some form or fashion of software license agreement, including free software and open source software which are usually distributed under the terms of their EULA.

Failure to abide by the terms of the license can subject the violator to the default penalties for violations of intellectual property laws in and if so allowed by the geographic region of the licensor, as well as any contractually agreed-upon damages listed in the software license.

*from Wikipedia*