Processor or CPU( Central Processing Unit)

It is often called the brain of the computer. It does all the calculations and comparisons rapidly.
Its speed is mesured in hertz(Hz) i.e.

Some versions of CPU are : Core i3, Core i5, Core i7, AMD etc

Ports

Ports are sockets that are used to connect external devices.
Generally, a desktop computer's motherboard consists of
USB ports,
Serial port(ethernet,wifi, usb devices, hdmi)
Parallel port(printers, scanners, VGA) (very rare now a days)
Audio port,
Modem port,
Monitor port

Cards

Cards are the devices that enables the user to configure(arrange or put together) or customize a computer to perform specific tasks or to enhance its performance.

A TV tuner card connect to PCI (Peripheral connecting interface) slots. PCI is an older technology that is being phased out. PCIe is a newer and faster technology that has become the standard for high-performance devices like graphics cards and SSDs

Expansion Card

Expansion cards are connected to the sockets of Motherboard called expansion slots.
Expansion slots are sockets on Motherboard that allows us to attach devices such as sound card, graphic card, network interface card etc to the computer in order to expand its working capability and performance.

Kinds of Expansion Cards

NIC--> Network interface card
Used for exchange of data between computer and network.
Sound Card-->
Used for producing sound, record sound, and to edit or mix sound

Graphic Card-->
Helps us to process and display videos. Modern GC contains memory, so RAM is not used for storing data.

PORTS
An interface between the computer and the peripheral devices like mouse, keyboard, monitor, printer, speaker, flash drive etc

A serial port : transmission of data happens serially i.e. one bit at a time.
Example: USB port

A parallel port: transmission of data occur parallely or simultaneously. Example: Industrial Printer

VIDEO PORTS

Display Port: High resolution used for high end gaming.

HDMI(High Definition Media interface):

VGA (Video Graphics Array )

DVI : (Digital Video Interface )
it was developed to replace the VGA technology