Flock and foil are techniques of screen printing (can also be done free hand) where glue is applied to the chosen substrate by means of the silk screen instead of pigment. Materials such as flock or foil can then be laid over the glue and adhered by means of heat such as an iron or hot press.
Flock is a kind of material that is responsible for velvet or suede textured print. The flock material is produced by applying tiny filaments to a substrate coated with adhesive; the 'flock' is electro statically charged and tends to stand up giving it a fine furry texture. Flock is available in a myriad of colours and even textures.
Pretty much what it says on the tin a foil like material which can be applied using the above method which comes in a mass of colours and gives a wonderfully shiny affect.