A motherboard is the glue that holds all the components of a computer together. Every component connected/installed/connected directly or indirectly to a system has a connection to the motherboard because it is the base on which the system and its components/peripheral devices stand and function. Technically speaking, the motherboard is a PCB printed circuit board that provides an interconnection for almost all the components present in a PC. It is also known as system/main board.
There are several functions that a motherboard performs. The important ones are the following:
· It acts as a glue that holds all the components together. Its main function is to coordinate the various operations carried out by the different components.
· Serves as an interface for all the unique modular components of a system such as Central Processing Unit – CPU, Random Access Memory – RAM, Storage Device – Hard Disk (Magnetic or Solid State)
· Provide slots and expansion cards to enhance the functionality of a system. Every day new devices with new interfaces are being developed. The motherboard needs to provide the slots to include the functionality.
· To supply power to the various components and devices as per their requirements.
CHIPSET
We all understand one simple fact; To make a system work, there must be a Central Processing Unit – the brain of a computer. Processor is the one that controls the functionality of the machine. But as it is clear from the above, there are many components or peripheral devices present in a computer. Therefore, there needs to be a suitable channel or medium for effective and efficient communication between the processor and other components. This task is taken over by Chipset .
It consists of 2 parts: Northbridge and Southbridge.
These two separate units control the memory cache, external bus, and component/peripheral device loads. The fast end of the hub is known as the Northbridge, and the slow end is known as the Southbridge.
The main reason the chipset is split into two separate units is that it is difficult to integrate the various components into a single chip. And furthermore, the speed of access/transfer of instructions/commands/data between processor and other components (some of the components process/interpret slowly) is different, so Northbridge provides fast access as compared to Southbridge. 
Northbridge is the part of the chipset that communicates with the processor. As its interaction is with the processor, it is fast. It acts as an intermediate channel between processor and memory, level 2 cache and AGP – Accelerated Graphics Port. Southbridge is slower than Northbridge and connects and controls computer input and output functions. It controls Universal Serial Bus – USB, the Basic Input Output System – BIOS, serial ports, etc. In other words, we can say that they control all functionalities except memory and AGP.
FORM FACTOR
This is a specification format for a motherboard. Simply speaking, we know that motherboard consists of several components . Now all components, slots, ports, etc. can be organized in various ways. But this will lead to problems and chaos as all manufacturers will follow their own convenient and suitable format. Therefore, there are specifications or format sets that define the shape and size of the motherboard. It specifies the motherboard layout .
The most common and famous factors are shown in the figure:
The names displayed are the various form factors. They are the standards. For example, ATX was created by Intel in the year 1996. According to this standard, the maximum motherboard size can be 12 * 9.6 inches. 305*244mm. The main features of the ATX standard are the rear panel ports, including parallel, serial, keyboard, mouse, USB, audio I/O, S/PDIF, and LAN. They are still one of the most used specifications, with some advances in the form of their variants.
MEMORY
When we hear the term memory, we think of storage devices, but for the processor the real memory is RAM – Random Access Memory. This is where the actual processing/execution/operations of data/commands/instructions take place. The execution speed (opening, closing, editing, copying, etc.) of files depends on this memory. The more RAM, the faster the processing.
Nowadays memory comes as DDR – Double Data Rate . The one shown in the figure has 128 MB DDR seen from the RAM. Nowadays the motherboard has several memory slots. In the motherboard diagram shown earlier, it has 2 memory slots. The multiple memory slots ensure that advanced versions of RAM can be installed and used in the system. For example, if we consider the present case, there are DDR3 which are mainly used in today's systems. But most of the previous chipsets do not have DDR3 RAM slot, that is, they do not support DDR3 RAM. Therefore, the system needs to have a new motherboard to support DDR3 RAM.
BUS
Buses are the pair of wires or a circuit used to transfer data. The greater the bus capacity, the faster the execution of a process/request. Bus speed (rate at which data is transferred) is measured in terms of MegaHertz.
This is the most important part of the motherboard that we tend to forget. To understand this concept, let us consider an example. Let's say there is a road with 5 lanes for car traffic. Now there is a river and henceforth a bridge made over a river. But on the bridge there are only 3 lanes. So the 2 cars that are outside need to wait. This can be better understood by the figure.
The same happens with buses on the computer. Bridge and bus are the same. What will be the use of 5 lanes on the road if 5 cars cannot pass over the bridge? Similarly, what will be the use of a component, say processor, that can access 5 bits simultaneously if the buses can only transfer 3 bits at a time? Processor efficiency will also access 3 bits at a time. Therefore, this is an important factor that must be taken into account if we want to improve the efficiency of the system.
There are several buses that are present in the system. Some of the important ones are as follows.
· System bus
· Front side of the bus
· Rear bus
· Control bus
· Address bus
· AGP bus
· PCI Express bus
· PATA, SATA, SCSI and their variants
· And many more…
BIOS
This is also known as firmware. This is read-only memory or flash memory. When the system is turned on, it needs to be started by loading the operating system. But where is the operating system present. It is present on the hard drive. So someone needs to tell where the operating system is located. This is done by the BIOS. At first, the registers return to the default value and then the BIOS begins its functions. It drives POST power on self-test. It checks whether all the most important and necessary components, e.g. The memory is either present or not. There's no error. If not, proceed to the next process which locates the Bootloader and therefore loads the operating system.
There are many more components present, for example. CMOS battery that keeps the clock running even when the power is off. This leads to the correct time even when we turn on the machine after a long period of time. There are also many more connections to manage other functionality. But whenever someone buys a system, the motherboard should also be one of the things they pay attention to.