CPU is short for "Central Processing Unit". It is also more commonly known as "The Processor". In simple terms the processor is the brains of your computer. The processor is responsible for handling most instructions and calculations it receives from hardware & software components on your computer. Therefore without a processor chip installed, your computer cannot operate.
RAM (Random Access Memory) is a place for your computer to read & write data that needs to be accessed by the CPU. Also more commonly it is referred to as "memory". The more RAM your computer has, potentially the faster it can run. Your CPU accesses data from the RAM. Therefore your computer will not operate without RAM. Modern RAM is literally 100's of times faster than the storage drive. The more data that can be accessed directly from the RAM, the faster the computer runs. If the amount of data being accessed is more than RAM capacity, then the RAM will temporarily save part of the data to the storage drive to make room. When this happens your computer will slow down. RAM is also considered volatile memory. This means as memory it is temporary. When you turn your computer off, all data is lost. Many times when you change a task, all or part of the data on the RAM is lost and you start over. This is why every computer has a storage drive, whether hard drive or solid state drive. A hard drive is permanent with or without power.
Since 2002 RAM has progressed as DDR, DDR2, DDR3, DDR4 and now DDR5. DDR stands for (double data rate). DDR RAM can process 2X as much data at the same speed as the previous SDRAM could. DDR2 processes 4X as much data at the same speed, And DDR3 processes 8X as much data at the same speed and so on with DDR4 & DDR5. These types of RAM correspond to development of computers. DDR5 being the latest. Note that these RAM technologies are not interchangeable with each other due to technoloy & physical configurations.
In simple terms, the "Motherboard" is the back bone, or central nervous system of your computer. It serves to connect all of the various components of your computer together, to function as a computer. The CPU, RAM, hard drives, solid state drives, optical drives, video cards, sound cards, and other ports and expansion cards all connect to the motherboard directly or via cables. Motherboards vary greatly in respect to the types of components they support. For example, each motherboard supports a single type or a group of types of CPU's, but not all. As well they support a list of RAM types, but not all. Additionally, some video cards, other drives and other peripherals may not be compatible.
The storage drive in todays computer world could be a ( hard disk drive, HDD) or a (solid state drive, SSD).This drive which ever it is, is a non volatile random access digital storage device. That means that when you turn your computer off and then back on, your data is still there. Data is only lost if it is intentionally deleted, or the drive becomes damaged and stops functioning. All of your data, all of your software, all that your computer does is stored on the storage drive. Obviously if your storage drive fails you loose everything. This is why it is recommended that you always back up your data on some form of external drive which is not a part of your computer. In some cases secondary drives may be required for backup. In some cases multiple back up drives may be required. This all depends on how important your data is.
A video is the hardware component that renders what you do on your computer so it can be viewed on your monitor or tv that is connected to your computer. There are two type of video graphics, onboard and add on. Most computers come with onboard graphics. That means that the CPU provides graphics processing as well as central processing. However in this situation graphics processing is limited. Onboard graphics will most likely be insufficient for tasks like gaming or video editing. This brings us to the second option, an add on video card. An add on video card can meet any need you have. It's a matter of compatibility and how much you want to spend. The add on video card has its own graphics processor (GPU) and its own Video memory (RAM). This can make the computer run faster since the CPU does not have to process the graphics. Most of the time a computer with an add on card is more of a custom built computer.