Since there is a lot of confusion about CAD files, I thought some of this would be helpful.

Almost every CAD program has their own binary CAD format.

And most CAD formats have many versions! For example:

AutoCAD 12 cannot read AutoCAD 14 DWG any more than Word 97 can read Office XP docs.

I’ve opened the gathering - http://en.wikipedia.org/wiki/Category:CAD_file_formats while looking for formats and found some.

Here is the excerpt:

3

• 3D InterOp

A

• ACIS
• ArchiCAD library part
• AutoCAD DXF

C

• CAD data exchange
• COLLADA
• Caltech Intermediate Form
• Catia Graphical Representation
• CircuitLogix

D

• DGN
• Design Exchange Format
• Design Web Format
• .dwg

E

• EDIF
• Electronic circuit simulation
• Excellon file

G

• G-code
• GDSII
• Geometric Description Language
• Gerber File

I

• IBIS Interconnect Modeling Specification
• IGES
• ISO 10303
• ISO 13399
• Input Output Buffer Information Specification
• Intergraph Standard File Formats

J

• JT (visualization format)

L

• List of STEP (ISO 10303) parts

M

• MD3 (file format)

O

• Obj
• Open Artwork System Interchange Standard
• Open Design Alliance

P

• PLY (file format)
• Parasolid

S

• SPICE
• STL (file format)
• SUGAR (MEMS Simulator)
• Simulation software
• Standard Parasitic Exchange Format

V

• VDA
• VDA-FS

There are some "more or less generic formats" used for exchange. Here are some:
DXF (many versions over the years)
IGES (Current version 5.3 ?)
STEP (*.stp - be careful of this one - several versions called "application protocols)
STL (for polygon models)
XYZ (just coordinate data for "point cloud")
DWG (Autodesk proprietary made public by ODA see http://www.opendwg.com/)
ACIS *.sat 3D Solid ModelsParasolid x_t 3D Solid Models
HPGL - Hewlett Packard Plotting data files
SVG - A new XML vector data format, could be used in CAD

That’s just the tip of the iceberg. Almost every CAD has their own format: http://en.wikipedia.org/wiki/List_of_CAD_companies

It is possible to convert between CAD formats. Several things are required. Both formats must support the entities (CAD object types) that are being converted. A software program is also needed that can provide the actual translation.