This will be an introductory talk on sub-wavelength optical projection lithography. "Sub-wavelength" refers to the fact that the features in the CPU and memory of your PC are smaller than the wavelength of the light by which those features are printed. Field and wave nature of light are impossible to ignore when imaging in the sub-wavelength scale. Therefore, designing chips today involves EM wave modeling of optical projection. The talk will give a flavor of fundamental limits of resolution, resolution enhancement techniques, approximations and numerical algorithms used to model projection lithography and their shortcomings.