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GUIDs

InstallShield 2015

GUID stands for globally unique identifier. A GUID is 128 bits long, and the algorithm used to generate a GUID guarantees each GUID to be unique. Because GUIDs are guaranteed to be unique, they can be used to identify COM classes, Product Codes, and various other codes.

For example, after a product is installed, a key is created under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall and is named after the installation’s Product Code. At one time, this key was named after the Product Name. However, this caused a potential conflict. If two installations were installed on the same machine, and both shared the same Product Name, they would also share the same registry key. Because a GUID is now used, it guarantees that this conflict does not occur.

An example GUID is {5D607F6A-AF48-4003-AFA8-69E019A4496F}. Any letters in a GUID must be in uppercase.

GUIDs in Your Project

When you create an installation project, there are a number of different GUIDs that are relevant to your project.

Project: For information on when you need to change GUIDs in a Basic MSI or InstallScript MSI project, see Major Upgrade vs. Minor Upgrade vs. Small Update.