Questions:

1."The peripheral’s address is 0x40. First the controller sends a byte with 0x40 + 0 in the final bit, indicating that it plans to write a command to the peripheral. All of this data is sent valid on the rising edge of the clock. Then the controller sends a command, 0x03, which means “tell me your object’s temperature” to this particular IC. Then the controller sends a byte with the peripheral’s address again, 0x40 +1 in the final bit."

What does the address ox4o mean? what is the rules of these address?

SPI.transfer(address);

SPI.transfer(value);

// take the SS pin high to de-select the chip:

What is SS pin and why we need to de-select the chip? What is going on when SPI.transfer(address) & SPI.transfer(value)?