Type of diffraction:-

1. Fresnel diffraction : in this type of diffraction, the source and screen are at finite distance from the obstacle.
   

   e.g. diffraction at a straight edge, small opaque disc, narrow wise etc.

2. Fraunhofer Diffraction:- in this type of diffraction, the source and the screen are at infinite distance from the obstacle.e.g. diffraction at single slit, double slit etc.