Dive into an intermediate-level video tutorial on General Purpose Input and Outputs (GPIO) for Arduino and ESP8266/ESP32 projects. Explore essential concepts including digital and analog inputs/outputs, logic levels, floating inputs, pullup/pulldown resistors, PWM, ADC, and high current applications. Learn about port expanders and their practical applications through two examples: connecting an LCD display output and a matrix keypad input using only two GPIO pins via I2C interface. The 44-minute video covers topics such as PCF8574 and MCP23017 port expanders, Arduino code implementation, and alternative expander options. Gain valuable insights to enhance your microprocessor projects and efficiently manage GPIO resources.