This comprehensive review charts the pivotal 17-year evolution of the Espressif Systems ESP microcontroller series (2008–2025), analyzing its transformative impact on the global Internet of Things (IoT) landscape. The article establishes a detailed chronological timeline, tracing the development from the foundational Wi-Fi modules like the early ESP8089 (2013) to advanced, multi-core platforms such as the RISC-V-based ESP32-P4 (slated for 2025). We provide a meticulous analysis of the key architectural and feature innovations across generations, specifically focusing on: Transition to RISC-V: Examination of the shift from the original Xtensa architecture to advanced RISC-V processor implementations. Next-Generation Connectivity: Review of the integration of cutting-edge wireless standards, including Wi-Fi 6 and enhanced Bluetooth/BLE capabilities. Edge Intelligence: Analysis of the introduction of dedicated AI acceleration hardware for on-device machine learning and edge computing tasks. Comparative Analysis: A data-driven comparison of specifications, power consumption, security features, and development ecosystems across all major chip families (ESP8266, ESP32, ESP32-S/C/H/P series). By unifying historical context with technical deep dives, this review highlights how Espressif democratized connected technology, making it an essential, unified reference for engineers, researchers, and developers in the embedded systems and IoT fields.

Keywords : This detailed review traces the evolution of Espressif’s ESP series microcontrollers, from the ESP8266 to the latest ESP32 variants, including ESP32-S2, ESP32-S3, ESP32-C3, and ESP32-P4. It covers Wi-Fi and Bluetooth Low Energy (BLE) technologies, RISC-V and Xtensa architectures, low-power IoT applications, AI acceleration, and edge computing. Ideal for embedded systems developers, IoT enthusiasts, and electronics engineers, this review highlights ESP microcontroller performance, system-on-chip innovations, smart home and industrial IoT applications, and future trends in wireless communication and IoT development (2008–2025).