Excel Services is part of Microsoft SharePoint Server 2010. Excel Services is built on ASP.NET and SharePoint Foundation technologies. Following are the core components in Excel Services:

• · Excel Web Access
• · Excel Web Services
• · User-defined functions (UDFs)
• · ECMAScript (JavaScript, JScript)
• · Representational State Transfer (REST) service
• · Excel Calculation Services

The Excel Web Access, Excel Web Services, UDFs, ECMAScript, the REST service, and Excel Calculation Services components can be divided into two major groups: the components on a front-end server (also known as the "Web front end") and the component on a back-end application server.

An important aspect of Excel Services is that solution developers can use its power programmatically from their applications. These applications can be line-of-business (LOB) products or custom enterprise solutions that an organization develops internally.

Following are examples of these applications:

• · Multitiered applications, with the presentation layer implemented as a Web application (for example, an ASP.NET application) that calls Excel Web Services.
• · Applications within Microsoft SharePoint Server 2010, or integrated with LOB products.

There are five types of development that you can do by using Excel Services:

• · Develop solutions by using Excel Web Services
• · Extend the Microsoft Excel function library in Excel Services by using user-defined functions (UDFs)
• · Customize the Excel Web Access Web Part
• · Develop solutions by using ECMAScript (JavaScript, JScript)
• · Use the REST API to perform operations against Excel workbooks

For more info, see