A PACKAGE describes the installation of a full product (Windows Installer does not handle dependencies between products) and is universally identified by a GUID. A product is made up of components, grouped into features.

Components:

A component is the minimal part of a product—each component is treated by Windows Installer as a unit: the install developer cannot, for example, use a

condition to specify to install just part of a component. Components can contain files,groups of files, directories, COM components, registry keys, shortcuts, and other data. The end user does not directly INTERACT with components.

Components are identified globally by GUIDs, thus the same component can be shared among several features of the same package or multiple packages, ideally through the use of merge modules (although, for this to work correctly, different components should not share any sub-components).

Key paths:

A key path is a specific file, registry key, or ODBC data source that the package author specifies as critical for a given component. Because a file is the most common type of key path, the term key file is commonly used. A component can contain at most one key path; if a component has no EXPLICIT key path, the component's destination directory is taken to be the key path.

When an MSI-based application is launched, Windows Installer checks the existence of these critical files or registry keys (that is, the key paths). If there is a mismatch between the current system state and the value specified in the MSI package (e.g., a key file is missing), then the related feature is re-installed. This process is also known as self-healing or self-repair. No two components should use the same key path.

Features :

A feature is a hierarchical group of components—a feature can contain any number of components and other features (a feature contained in another feature is called a "subfeature"). Most installation programs display a "custom setup" dialog box at run time, from which the end user can SELECT which features to install or remove.

The package author defines the product features. A word-processing program, for example, might provide features for the main program executable, the program's help files, and optional spelling CHECKER and stationery modules.

A package describes the installation of a full product (Windows Installer does not handle dependencies between products) and is universally identified by a GUID. A product is made up of components, grouped into features.

Components:

A component is the minimal part of a product—each component is treated by Windows Installer as a unit: the install developer cannot, for example, use a

condition to specify to install just part of a component. Components can contain files,groups of files, directories, COM components, registry keys, shortcuts, and other data. The end user does not directly interact with components.

Components are identified globally by GUIDs, thus the same component can be shared among several features of the same package or multiple packages, ideally through the use of merge modules (although, for this to work correctly, different components should not share any sub-components).

Key paths:

A key path is a specific file, registry key, or ODBC data source that the package author specifies as critical for a given component. Because a file is the most common type of key path, the term key file is commonly used. A component can contain at most one key path; if a component has no explicit key path, the component's destination directory is taken to be the key path.

When an MSI-based application is launched, Windows Installer checks the existence of these critical files or registry keys (that is, the key paths). If there is a mismatch between the current system state and the value specified in the MSI package (e.g., a key file is missing), then the related feature is re-installed. This process is also known as self-healing or self-repair. No two components should use the same key path.

Features :

A feature is a hierarchical group of components—a feature can contain any number of components and other features (a feature contained in another feature is called a "subfeature"). Most installation programs display a "custom setup" dialog box at run time, from which the end user can select which features to install or remove.

The package author defines the product features. A word-processing program, for example, might provide features for the main program executable, the program's help files, and optional spelling checker and stationery modules.