What are the applications of diffraction of light?

Answer 1

Here are some sites on light diffraction:
http://science.jrank.org/pages/2063/Diffraction.html
http://www.phy.davidson.edu/StuHome/cabell_f/diffractionfinal/pages/fraunhofer.htm
http://www.physlink.com/education/askexperts/ae434.cfm