Microsoft Windows SharePoint Services 3.0 introduces a deployment mechanism named "solution packages." A solution package is a CAB file with a .wsp file-name extension that contains all the files that must be deployed on the front-end Web server and a set of XML-based installation instructions. Windows SharePoint Services provides a rich infrastructure that simplifies deployment of solution packages in a Web farm environment.
Each solution package must contain a header file named manifest.xml that defines a Solution element. The following manifest.xml file has been created for the Item Auditing solution.
As you see, the manifest.xml file defines which files are parts of the solution that must be deployed on the front-end Web server. After you define the manifest.xml file, compile it into a CAB file with all the other required files. You can do this by using the MAKECAB.EXE command-line utility. When you use this tool, you must define a .ddf file that instructs MAKECAB.EXE which files to include in the output CAB file. Here is an example of a file named cab.ddf file used for building the ItemAuditing.wsp package file for the Item Auditing solution.
Because you can deploy SharePoint solutions on Windows SharePoint Services or Microsoft Office SharePoint Server installations that range in size from a single, stand-alone Web server to large enterprise server farms, there must be a mechanism to deploy them as a single unit. By deploying a single unit, we can have a supported, testable, and repeatable deployment mechanism. The deployment mechanism that SharePoint Products and Technologies use is the solution package.
Solution packages are critical components for deployment in enterprise or commercial scenarios, and use the same Microsoft Visual Studio project formats you use in your development environment. For all deployments outside your development environment, use solution packages. Solution packages also enable your system administrators to create scriptable installations, an important requirement for many enterprise-class IT organizations.