A lot of people these days are opting to build a computer themselves, rather than buying a ready-made one. By doing this, you have the liberty of getting the exact configuration you desire and also freedom to choose good quality and genuine parts. While buying parts to build your own PC, you should go about it in a particular order, as a lot of these components are interdependent, like a motherboard and processor or motherboard and drivers. Assembling Your Own PC Case The computer case you choose will determine settings of all the internal parts and also the look of your machine from the outside. A good, strong case will make it easier for you to place all internal parts properly along with protecting them from possible damage by external sources. Cases come in various sizes and you need to choose the one which suits your requirements the best. Mid-tower, is the most popular choice, as it has enough space within to hold all internal components. CPU The CPU or Central Processing Unit, is the heart of every computer, as it is responsible for the performance. The four main factors you need to bear in mind while picking up a CPU are - Socket type, FSB Speed, Model/Speed number, and the packaging. Every CPU needs a cooler and most of them come with one. In case your CPU does not have a cooler, buy one separately. Higher the FSB speed, the better. Consult your seller regarding the model numbers, as he will be able to suggest the one which suits your requirement. Intel and AMD are the most preferred choices when it comes to processors. Motherboard This is another essential component which has a huge impact on performance. The motherboard will determine what processor you can use, the various drives you can attach, the type of memory that can be used and also what external devices can be attached to the computer. If you are looking for a high-end computer which requires installation of sound cards, graphic cards, or any other drivers, pick a motherboard which will support all these. It will be a little expensive than a basic one. Again, consult your seller regarding the various brands and model numbers of available motherboards in the market. Drives All the data on the computer gets stored on a hard drive. Size, connection speed, and RPM speed need to be taken into consideration while selecting a hard drive. It is recommended that all modern PCs should have hard drives with at least 100GB storage capacity. Don't go below that. The maximum size is then determined by keeping in mind your usage. Higher the storage size, higher the price. Optical drives can also be included. CD-ROM, DVD-ROM, and DVD writer are different types of optical drives. Maximum people go with a combination of DVD writer + CD writer when it comes to optical drives, as it makes life easier by facilitating file, music, or movies storage and sharing. Floppy drives are virtually extinct, so you can conveniently skip them as well. Expansion Cards The various network, video, sound, and graphic expansion cards available in the market improve the quality and functionality of your system in a big way. Your motherboard will determine how many and which expansion cards you can use. Most motherboards nowadays come with a basic graphic card, which is enough for everyday requirements. If you are looking for high-end graphics for gaming or heavy graphic related work , then you will have to attach a graphic card to your motherboard. Operating System The operating system acts as an interface between the user and the machine. Pick an operating system which you are comfortable with or which will support your work. The popular operating systems available in the market are Windows Vista, Windows 7, Windows 8, Linux, and Mac OS. Normally, Windows 7 should be enough for basic use, while Windows 8 is more suited for professional and high-end usage. And yes, buy original versions, please. Memory The memory consists of RAM (Random Access Memory) and ROM (Read-only Memory). Of these, RAM is the one which needs attention, as it impacts your operating speed to a great extent. Higher the RAM, the better. 1GB is the minimum RAM you should have for it to function smooth and fast. This will be enough for home use, but high-end users should go for at least 4GB RAM. Your motherboard defines the type of memory you can install, but most of them these days support Double Data Rate (DDR) memory. A very important point to be kept in mind while picking up the memory is ,buy the memory type which is equal to or more in speed than your processor's actual FSB speed. Input/Output Devices Next, you will have to buy all the input and output devices, which will be attached to your computer. A mouse and keyboard is used to feed, manage, and organize data in the system. A Monitor is a must to view contents of your system. There is not much to differentiate between the types of keyboards and mice available in the market. Buy branded ones, which have a good warranty period. Also, get a smooth mouse pad for your mouse. Monitors have variants like flat screen, LCD, plasmas. They also come in several sizes like 14", 18", or 21". Pick whatever you are comfortable with. Consult websites or friends and go through user reviews to get a better idea on the input/output devices. Printers, headphones, speakers, and scanners are other optional devices you can buy as per your needs. After procuring all the parts mentioned in above, you can start building a computer step by step. There are various guides available in bookstores or on the internet, which you can use.