Data is sent in 8-bit bytes, most significant bit first, with each byte followed by an ACK/NACK bit.
SDA and SCL are connected to a voltage source via pull-up resistors, allowing devices to pull the lines low without creating short circuits. I2C Overview
Each slave device has a unique 7-bit (or 10-bit) address, eliminating the need for complex Chip Select (CS) lines used in SPI. Data is sent in 8-bit bytes, most significant