CMOS imagers have evolved during the last two decades to dominate the market of area imagers, with more than 90% of the total share. This evolution has been basically fueled by consumer applications (mostly cell phones) with the prevalent trends of decreasing the pixel pitch and with most relevant challenges focused on the design and optimization of the photo-sensor devices themselves. Although cell phones will remain the dominant applications for CMOS imagers, the market volume for other applications (such as machine vision, surveillance, military applications, X-ray imagers, medical, etc.) is forecasted to reach some 0.7billion units in 2015. For many of these applications image resolution, although undoubtedly important, must be complemented with other features such as speed and smartness. For instance, sensors intended for surveillance applications should be capable to analyze complex spatial-temporal scenes and combine high-quality image recording of significant events with high-speed decision making. Just to mention another example, scientific applications call for the smart selection of salient points and region-of-interests and for the ultra-high-speed downloading of the so selected areas. Finally, machine vision sensors (employed for instance for inspection) require image content analysis and decision making to be made with largest possible throughput. All these features require the incorporation of processing circuitry together with the photo-sensing and readout circuitry themselves and define the category of the so-called smart-cameras-on-chip. This lecture overviews the art of CMOS Smart Image Sensors including emerging areas like MOS-SPADs, 3-D Capture, THz sensing, High Dynamic Acquisition, Content-aware sensing, etc.