ClosedXML makes it easier for developers to create Excel 2007/2010 files. It provides a nice object oriented way to manipulate the files (similar to VBA) without dealing with the hassles of XML Documents. It can be used by any .NET language like C# and Visual
What can you do with this?
ClosedXML allows you to create Excel 2007/2010 files without the Excel application. The typical example is creating Excel reports on a web server.
If you've ever used the Microsoft Open XML Format SDK you know just how much code you have to write to get the same results as the following 4 lines of code.
var workbook = new XLWorkbook();
var worksheet = workbook.Worksheets.Add("Sample Sheet");
worksheet.Cell("A1").Value = "Hello World!";
Something more elaborate:
The Documentation page has an example of how to create the following table (Showcase) as well as many other examples: