Nagware

Shareware is a type of proprietary software which is initially provided free of charge to users, who are allowed and encouraged to make and share copies of the program. Shareware is often offered as a download from an Internet website or as a compact disc included with a magazine. Shareware is available on all major personal computer platforms. The term shareware is used in contrast to open-source software, in which the source code is available for anyone to inspect and alter; and freeware, which is software distributed at no cost to the user but without source code being made available.

There are many types of shareware, and while they may not require an initial up-front payment, all are intended to generate revenue in one way or another. Some limit use to personal non-commercial purposes only, with purchase of a license required for use in a business enterprise. The software itself may be limited in functionality or be time-limited, or it may remind the user that payment would be appreciated.

Adware, short for "advertising-supported software", is any software package which automatically renders advertisements in order to generate revenue for its author. The advertisements may be in the user interface of the software or on a screen presented to the user during the installation process. The functions may be designed to analyze which Internet sites the user visits and to present advertising pertinent to the types of goods or services featured there. The term is sometimes used to refer to software that displays unwanted advertisements.

On Microsoft Windows, shareware is often packaged with adware. During the install of the intended software, the user is presented with a requirement to agree to the terms of click through licensing or similar licensing which governs the installation of the software.

Demoware is a demonstration version of software. There are generally two types demoware: that which is crippled, and that which has a trial period.

In software, crippleware means that vital features of the program such as printing or the ability to save files are disabled until the user buys the software. This allows users to take a close look at the features of a program without being able to use it to generate output. The distinction between freemium and crippleware is that an unlicensed freemium program has useful functionality, while crippleware demonstrates its potential but is not in itself useful.

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Wikipedia