Adobe's EPS format (Encapsulated PostScript) is perhaps the most common vector image format.It is the standard interchange format in the print industry.It is widely supported as an export format, but due to the complexity of the full format specification, not all programs that claim to support EPS are able to import all variants of it.Adobe Illustrator and recent versions of CorelDRAW have very good support for reading and writing EPS.Ghostview can read it very well but does not have any editing capabilities.Inkscape can only export it.
SVGThe W3C standard vector image format is called SVG (Scalable Vector Graphics). Inkscape and recent versions of Adobe Illustratorand CorelDRAW have good support for reading and writing SVG. Further information on the SVG format may be found on the official SVG website.
PDFAdobe's PDF format (Portable Document Format) is very widely used as a general purpose platform-independent document format.And while it is not exclusively used as such, it is also a very good vector image format.Adobe gives away the Acrobat PDF reader, but sells the tools required to create PDF files(third party tools that perform the same task are also for sale). Those tools work with any program that is able to print.Support for reading and editing PDF files is much more limited.
AIThe native format of Adobe Illustrator is the AI format (Adobe Illustrator Artwork), a modified version of the older EPS format.The AI format is fairly widely supported, but is less ubiquitous than the EPS format, and most programs that read AI can also read EPS.
DXFDrawing eXchange Format.A CAD format from Autodesk, used by CAD tools from many different vendors.Some programs have difficulty reading DXF files with splines (curves), so the Desktop Edition supportsline+spline as well as line only output modes.