Microsoft Visual Studio Tools for the Microsoft Office System provides a new set of Visual Studio .NET 2003 project templates you can use to create assemblies that run in process with Microsoft Office Excel 2003 and Microsoft Office Word 2003. This enables you to create document-centric solutions that utilize the power of the hosting application, which, in this first release, includes Excel and Word. Using either Microsoft Visual Basic .NET or Microsoft Visual C# , you create assemblies that execute under the control of the common language runtime. This code is often referred to as managed code. In contrast, existing Visual Basic for Applications (VBA) or COM-based code is referred to as unmanaged code.

The common language runtime manages memory and validates your code to make sure it doesn't attempt to perform illegal operations such as access memory that doesn't belong to it. In addition, the runtime provides access to the Microsoft .NET Framework and the Base Class Libraries. With these tools, you could, for example, create a document management system that validates documents for legal correctness. Or you could create a sales forecasting solution that uses Excel for the user interface while automatically updating a central database when projections are changed. The possibilities are only limited by your imagination to leverage the rich object models exposed by Excel and Word coupled with your custom code and rich libraries provided by the .NET Framework.

Although it is possible to automate Excel or Word from managed code, doing so requires an external application manipulating the particular Office application from the outside. Assemblies produced with Visual Studio Tools for the Microsoft Office System enable managed code to work with the hosting application at a more intimate level. Although it's possible to create a COM add-in using managed code, the new framework provided by Visual Studio Tools for the Microsoft Office System enables you to create a solution that is tightly integrated and, more importantly, specifically designed to use managed code.

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