SharePoint and Enterprise Portal file extensions explained

So, just a quick primer on common file extensions in SharePoint and EP.

• *.cab = Cabinet File, a setup file from the olden days that can be made using MAKECAB.EXE. It includes a manifest.xml telling what do to and where, and the folder structure within the cab is important when deploying.
• *.wsp = Windows SharePoint solution. This is essentially a modern day cab file, and IS a renamed cab file. For more info check out: http://msdn.microsoft.com/en-us/library/aa543741.aspx Note that changing the extension back to .cab again will allow you to take a peek inside.
• *.dwp = Web Part. This is the pre-ASP.NET 2.0 SharePoint web part format. Remember that web parts originated in SharePoint and that the ASP.NET team found the idea so appealing that they brought it into ASP.NET 2.0. In SharePoint 2003 and earlier web parts were a SharePoint specific phenomenon (though they borrow heavily from Lotus portlets and similar, but that is another matter).
• *.webpart = Web Part. This is the ASP.NET 2.0+ web part format. It is the recommended format of modern day SharePoint web parts.

Note: dwp and webpart files are deployed in... you guessed it: A cabinet file, errr, I mean wsp file.