This document discusses smart sensors and intelligent sensors. It defines smart sensors as sensors combined with interfacing circuits that allow two-way communication and decision making. Intelligent sensors are an evolution of smart sensors that add data processing, reconfigurability, and the ability to aggregate data from other sensors. The document outlines the architecture and generations of smart sensors from early devices with just sensor elements to current ones with memory, digital intelligence, and integrated analog-to-digital conversion. It provides examples of smart sensor applications and discusses their advantages of being more reliable and scalable while also having higher complexity and cost compared to simple sensors.