Dye
A dye or dyestuff is a colored and organic chemical compound which have
affinity to substance like textiles, absorbs light strongly in visible region
and create physical and chemical bond with the fibres.
Dye must contain chromophore and auxochrome group.
In case of organic compounds sometimes they have some molecules with pi-bond
e.g. -NO, -NO2 , -N=N- etc. for
which the compounds become colored and the molecules with pi-bond are
called chromophore. Auxochrome is attached to chromophore to
modify its absorption of light. –OH, -CHO etc. are auxochrome.