I2C is a serial communication protocol often used for short-distance, low-bandwidth communication between integrated circuits. While USB 2.0 offers significantly higher bandwidth and is used for connecting peripherals, I2C can be an alternative for internal chip communication or low-speed external connections, making them competitors in certain niche applications.

SPI is another serial communication protocol commonly used for short-distance, high-speed communication, primarily between microcontrollers and peripherals. Like I2C, it is used in applications where USB 2.0's speed and complexity are not needed. SPI and USB compete for similar embedded applications.