ESP8266 by Wikipedia

What is the ESP8266?
The ESP8266 is a Wi-Fi microcontroller with built-in TCP / IP networking software.

Who is the ESP8266 produced by?
The ESP8266 is produced by Espressif Systems.

Where is the ESP8266 produced?
The ESP8266 is produced in Shanghai, China.

What chip is similar to the ESP8266 but with 1 MiB of built-in flash memory?
The ESP8285 is a similar chip to the ESP8266 but with 1 MiB of built-in flash memory.

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What microprocessor does the ESP8266 have?
The ESP8266 has an L106 32-bit RISC microprocessor based on the Tensilica Diamond Standard 106Micro.

What is the clock speed of the microprocessor in the ESP8266?
The clock speed of the microprocessor in the ESP8266 is either 80 MHz or 160 MHz.

What Wi-Fi standard does the ESP8266 support?
The ESP8266 supports the IEEE 802.11 b/g/n Wi-Fi standard.

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How many GPIO pins does the ESP8266 have?
The ESP8266 has 18 GPIO pins.

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What is the successor to the ESP8266?
The successor to the ESP8266 is the ESP32 series.

Which successor chip is pin-compatible with the ESP8266?
The successor chip that is pin-compatible with the ESP8266 is the ESP32-C3.