Serial port is by far the fastest port. It is so fast that it is used in modern computer to connect hard drive to motherboard. Current generation of serial port is SATA 6Gpbs.
give the difference between serial port and parallel port
Depends, is the device serial or parallel?
parallel
Some key differences between a Serial and Parallel Adder are that a Serial Adder is slower, a Parallel adder is a combinational circuit and the time required for addition depends on the number of bits in a Serial, but not a Parallel. A Serial Adder is a sequential circuit while a Parallel is a combinational circuit.
multiplexer can be used as parallel to serial converter.
Usually serial. Parallel is almost completely gone, and serial is getting replaced by USB.
Serial
Lots of ports aren't found on sound cards. Examples include Ethernet, RJ-11 (telephone), USB, FireWire, USB, and typically serial or parallel ports.
A "serial to parallel" converter converts a serial data connection to a parallel data connection. For example, in computer storage, there are controller chipsets that convert SATA (Serial ATA) to PATA (Parallel ATA, also called IDE or EIDE).
parallel
It is less costly to design ever faster serial lines than to create and build the necessary circuitry to keep faster parallel channels properly aligned. This is why Parallel ATA and Parallel SCSI have migrated to Serial ATA (SATA) and Serial SCSI (SAS).
serial chip