CPU

• The CPU (Central Processing Unit) is the brain of the computer. It processes all tasks executed on the PC. CPU speed is one of the important metrics used to evaluate performance. A faster CPU will drastically improve the overall performance of your PC. CPUs are available in wide array of speeds ranging from 1 GHz to over 3.2 GHz.
  
  

RAM

• RAM (Random Access Memory) provides temporary data storage for applications on your PC. Having more RAM in your PC greatly improves system performance. The amount of RAM in a PC ranges from 2 GB to 16 GB.
  
  

Video card

• A video card displays video and graphics on your monitor. If you're going to be using the PC for gaming or video-intensive applications, choose a card with at least 512 MB of video memory.
  
  

Motherboard

• The motherboard integrates all the components of your PC, including the CPU, RAM and video card. One of the most important things to look for while purchasing a motherboard is compatibility with your CPU.
  
  

Hard drive

• A hard drive provides permanent storage for all the data on your PC. Having more hard drive space is a huge asset especially if you're going to be storing lots of movies, music, games, photos etc. Hard drives sizes range from 40 GB to over 750 GB.
  
  

Power supply

• The power supply provides power to all components of your PC. The minimum wattage rating for a power supply unit is about 250W; however, check the specifications of your video card carefully. High-end video cards need more power, so take that into consideration while researching power supplies.
  
  

CPU heat sink

• The CPU generates a substantial amount of heat while it's running. A heat sink dissipates this heat and prevents the CPU from overheating. Heat sinks are designed for specific CPU sockets, so be sure to check the compatibility of the heat sink with your CPU.
  
  

Computer case

• A computer case houses all components of your PC. It also provides an interface for USB, FireWire and Ethernet connections. If you're planning on having more than one video card, look for cases with extra room.
  
  

Operating system

• The operating system manages all applications on your PC. It coordinates and schedules execution of programs on your computer. Operating systems are typically available on a CD and are installed after your hardware setup is complete.
  
  

Monitor

• A monitor displays output from your video card. LCD monitors are the predominant choice for PCs. Monitor size is an important factor to consider: a larger screen size can significantly enhance your multimedia experience. Monitor sizes typically range from 15 to 21 inches.
  
  

Keyboard and mouse

• Most keyboards and mice connect to the PC through a USB interface. However, wireless keyboards and mice offer greater mobility and are becoming increasingly popular.