Files with .DOT extension are template files created by Microsoft Word to have pre-formatted settings for generation of further DOC or DOCX files. A template file is created in order to have specific user settings that should be applied to subsequent files created from these. These settings include page margins, borders, headers, footers, and other page settings. Such templates are used in official documents such as company letterheads and standardized forms.
A file with PPT extension represents PowerPoint file that consists of a collection of slides for displaying as SlideShow. It specifies the Binary File Format used by Microsoft PowerPoint 97-2003. A PPT file can contain several different types of information such as text, bulleted points, images, multimedia and other embedded OLE objects. Microsoft came up with newer file format for PowerPoint, known as PPTX, from 2007 onwards that is based on Office OpenXML and is different from this binary file format.
You can also convert DOT into many other file formats. Please see the complete list below.