Invisible or Concealed Zips are the most professional dress and skirt type of zip, where the design is not interupted by the appearance of the closure. Only the fine zipper puller is seen on the garment. (Tip - you can change the zipper puller colour with nail varnish!)
Japanese manufacturer YKK is the leading name in zipper manufacturing, for its durability and quality.
For help and tips on inserting Invisible / Concealed zips download YKK's helpful guide.
(Tip - you can iron the plastic zipper teeth to one side to help - don't use a hot iron though)