What is an ESP32?

ESP32 is a 32-bit processor from Espressif Systems with wifi and bluetooth connectivity.  It is a successor to ESP8266 (32-bit cpu and wifi) which became extremely popular with the make community because of its low price and wifi connectivity.  The Arduino IDE incorporated support for ESP8266 and ESP32 which gave hobbyists a simplified approach to build applications for the system.

The first ESP32 was first released in Sepember 2016 so the reange is now ten years old.  There are now two principal designs "S" and "C" based on Xtensa and RISC-V architecture respectively.

ESP32-S3 is based on dual core Xtensa LX7 processors.  Xtensa is marketed by Cadence Systems in San Jose, California.  These processors  can be customised to provide a specific set of functions which the manufacturer requires.  It looks like you can use an IDE to design your processor and it is manufactured based on the results.

ESP32-S3 is a SoC (System on a chip) with 240MHz dul Xtena LX7 CPU, 512KB SRAM (Static RAM), 384KB ROM, 16KB RTC RAM (Very Fast RAM), 8MB PSRAM (Pseudo-static slow RAM), 45 GPIO pins, 3 x UART.  Internal ROM is used internally for wifi drivers, RTOS etc.
The SoC is often combined with extra components in a module board such as ESP-WROOM-32. Mine is an ESP32-S3-N16R8 which has 16MB flash ROM as well as 8MB PSRAM.  The module is a square silver SMD component with an antenna.
The module is mounted on a development board with USB-C ports, 40 pins, boot/reset buttons and an RGB LED.  Mine doesn't have a name but there are some well-known ones: ESP32-DevKitC (Espressif), LolinD32 (Wemos), NodeMCU-32S (Ai-Thinker).

I found some interesting articles which provide more illumination on circuitschools and JLCPCB

I have previously blogged about the ESP32-C3 RISC-V processor. This is important as Espressif have announced they aim to focus on RISC-V in the future which implies that their RISC-V  cores will eventually be as powerful as Xtensa cores.

ESP32 uses the RTOS Real-Time Operating System internally to control hardware.  Programmers can use RTOS functions for time-sensitive operations.  Programming is carried out using ESP-IDF, Arduino or PlatformIO IDEs. Programming can be carried out in C, C++ or micropython.