The short answer can be given by using a quick comparison.  The most recognizable features of a window are the glass (of course), and the framing.  The framing material, which not only makes up the perimeter frame, but the surrounding frames of the operable parts of a window as well, is typically made of Wood, Aluminum or Vinyl.

So again, the short answer is a window that uses Vinyl as the framing material.

But to really answer this question, one needs to ask, What is Vinyl?

Vinyl is the common name given to an advanced polymer called Poly-vinyl Chloride, or “PVC”.

Yep PVC.  The PVC you’’ve probably heard of in pipes and window blinds.  It turns out that PVC, or Vinyl is used in all sorts of things.  PVC is in fact, one of the most used polymers in the world, being utilized in construction, transportation, medical devices and more.

I know what you’re thinking.  Is the PVC in your windows, the same PVC that is used in dialysis tubes?  OK, maybe you were’’t thinking that, but I was (and I think it’s a great question).  The answer is ‘no’.

You see, PVC itself is in fact a Polymer.  This is a term of Chemistry
describing a very large molecule, essentially.  What happens in real world use, is that certain additives are combined with raw PVC to produce a PLASTIC.   Despite the imperceptions that plastic means “cheap”, the term plastic actually describes a higher level material than the base polymer.  Polymer just sounds more fancy.

So back to the question about dialysis tubes and windows.

PVC is a safe, economical, thermally resistant material that can be used in many applications, it just needs modified to suit that particular application.

So when companies are making dialysis tubes, PVC is blended with certain additives that make it suitable for use in the medical application.  For instance, it may be blended with certain chemicals that make sure it doesn’’t react negatively with someone’s skin.

When it comes to Windows, PVC is blended with certain chemicals that allow it to be molded and extruded into window frames, and to resist being degraded by the sun.

So when someone says they’’ve installed Vinyl Windows in their home, they’re actually saying that they’’ve installed windows that have frames constructed of an advanced polymer that has been blended with various other chemicals into a modern technology marvel: plastic!

Sweet, eh?