Vintage?

I am often asked if something is vintage and what that means.  I stock a lot of pressed glass and embroidered tablecloths amongst other things, so what does vintage mean?  Recently an older couple where browsing through some glass on my stall, they asked if the items were new, and today I was asked if my tablecloths were new and just made to look old!  I'm not sure how I would do that......
I am beginning to research the glass, its fascinating, many items were produced in the 30's, 40's and 50's and other items are definately Victorian.  I also have some fabulous art deco pieces which are quite easy to identify.  Other pieces are recognisable as being by certain artists and so therefore easier to date. 
Vintage is a frequently used word  to describe something which is brand new but made to look old.  Older glass is often heavier, has a great sparkle, often has bubbles within the glass, has beautiful detail and most importantly has a purpose.
People who buy and love vintage pressed glass often use it for things other than its original purpose, dressing table trays to hold condiments and jams, large jugs to hold flowers, salts to hold candles to name a few.
I'm off to the carboot tomorrow to find more treasures - hope you all have a fab Mothers Day!