1. Add on cards

2. Also known as Expansion card or interface adapter. It can be inserted into an expansion slot of a motherboard to add functionality to a computer system via the expansion bus. One edge of the expansion card holds the contacts (the edge connector) that fit exactly into the slot. They establish the electrical contact between the electronics (mostly integrated circuits) on the card and on the motherboard. Based on the form factor of the motherboard the number of expansion slots varies.

3. Different types of expansion cards in a computer are 1.Network card 2.Sound card 3.Video card 4.Modem 5.TV tuner card

4. Video card Also called graphics card. It is a card used for generating and displaying images. A graphics card has its own RAM(VRAM),Processor(GPU) and video BIOS specifically for processing video images, and thus offloads this work from the CPU and system RAM. GPU is a dedicated processor optimized for accelerating graphics. Video BIOS controls the card’s operations and provides the instructions that allows the computer and software to interact with the card.

5. The memory capacity of most modern video cards ranges from 128 MB to 8 GB. Nvdia(GeForce) and AMD(Radeon) are main manufactures of graphics card. It is usually inserted in AGP slot.

7. Sound card Also called audio card. It provides a computer with the ability to produce sounds. Most of the motherboards have an integrated audio. Sound cards usually feature a digital-to-analog converter(DAC), which converts recorded or generated digital data into an analog format. Main manufactures are creative technologies, ASUS etc.

9. Network Card Also called Network Interface Card(NIC). It is a computer hardware component that connects a computer to a computer network. Every Ethernet network controller has a unique 48-bit serial number called a MAC address.

11. Modem It is a device that modulates and demodulate signals. External modems can be connected though serial port.

13. TV tuner card It is a device that allows television signals to be received by a computer. It is usually fixed in PCI slot.