Communication between devices of computer is almost always :

The correct answer is option 1: Serial data transfer

Key Points

• Serial data transfer involves sending data one bit at a time over a single communication line.
• Most modern communication between computer devices (like USB, SATA, Ethernet) is done via **serial transmission** due to:
  • Lower cost (fewer wires needed)
  • Better over long distances (less noise/interference)
  • Higher speeds using advanced signaling techniques
• Examples:
  • USB – Universal Serial Bus
  • Ethernet – Uses serial transmission for network data
  • Serial ports (COM ports) on older computers

Additional Information

• Parallel data transfer: Used in older systems (like IDE hard drives, internal buses), not preferred for external communication.
• Serial parallel / Parallel serial data transfer: Not standard terms; they mix concepts and are incorrect.

Hence, the correct answer is: option 1: Serial data transfer