Also known as the CPU (central processing unit) by Intel and CPU and APU (accelerated processor unit) by AMD, this is the computer's "brain," responsible for processing information. Performance is the most important factor, and is determined primarily by the number of cores it has and its clock speed.
Intel and AMD are the dominant processor manufacturers. Within each company's product lines are various processor families. Intel's include the Atom, Celeron, Pentium, and second-,third-, and fourth-generation Core; while AMD's include the Sempron, Athlon II, Phenom II, E-Series, A-Series, and FX. Intel's new CPUs are the third-generation Core i3, i5, and i7. They're setting a new standard in desktop performance by adding an automatic speed boost when needed and improved graphics and video capabilities. These processors are also available in laptops. AMD's new top processors are called A Series Elite. The A Series Elite integrates discrete graphics into the processor. As a result, you can play more challenging video games on these computers without needing separate graphics. They also add an automatic speed boost when needed and improved graphics and video capabilities.
Processors with multiple cores can process more data simultaneously. Check Intel's or AMD's website to determine how many cores a particular processor model has.
Clock speed, measured in gigahertz (GHz), determines how quickly a processor can process information. Generally within a processor family, the higher the clock speed, the faster the processor. Clock speeds typically start at around 1GHz for a mobile processor and can exceed 3GHz for a desktop processor. Processors can up the speed a bit for a brief time to get maximum performance.
Power consumption is another important factor when choosing a processor, especially for laptops--lower power consumption translates to longer battery life.
When buying a computer, make sure it has a processor that will be fast enough to handle your needs. Whether you're buying a desktop or a laptop, avoid computers that use the AMD Athlon Neo, Turion Neo, or Sempron processor, and the Intel Atom. For basic tasks such as browsing the Web and checking e-mail, opt for a low-end, lower-prcied processor such as the Intel Pentium, Celeron, or AMD A4 or A6. If you plan to use your desktop or laptop for entertainment, such as watching videos or playing games, get a faster processor such as the Intel Core i5 or AMD A8. If you're a gamer or plan to edit high-definition (HD) video, buy a computer with a high-end processor such as the Intel Core i7 or AMD A10 Series. For less-intensive uses such as productivity tasks, the Intel Core i3 should suffice.