A CDR file is a drawing created with CorelDRAW. It is saved in a proprietary vector graphic format that can be opened by Corel software programs.
About Corel CorelDRAW Graphics Suite
CorelDRAW is a vector illustration, tracing, page layout, and photo-editing program. It can be used to create illustrations, logos, brochures, flyers, signs, and other types of graphics. CorelDRAW can also create vector graphics from bitmap images. It is designed for both professional and occasional use.