Nanoimprint lithography, which has the advantages of precision, versatility, and 3D abilities, requires the repeated use of a mold to pattern prepared wafers in volume. After final deposition, wafers can be diced to size or can be run through the process again for more functional layers. Nanoimprint lithography is evolving as a manufacturing methodology that permits high-throughput wafer-scale production with the nanoscale lithographic resolution required to produce multifunction integrated sub-wavelength optical components. Standard photolithography is now able to create subsystem-100nm linewidths, but this resolution is not high enough to be generally useful for creation of practical sub-wavelength diffraction gratings. Among other lithographics approaches (nanoimprint lithography, soft lithography, and atomic-force microscope/dip-pen lithography) nanoimprint lithography has had the most commercial success so far in the area of availability of commercial manufacturing tools and in the increasing number of subwavelength optical components that are now available in volume. Nanoimprint lithography uses mechanical methods by a master mold to deform the layer of resist into a shape that can be used as an etching mask to obtain subwavelength-scale patterns and structures. With mechanical nanoimprint lithography, resolution limitations associated with lithography methods that use energy beams are eliminated. Nanoimprint lithography can also form 2D patterns and directly form 3D structures that can be used to create lens arrays. Among topics covered are essential attributes, challenges, advantages, and subwavelength gratings.