A single chip that contains two distinct processors that work simultaneously. IBM introduced dual cores in its Power 4 chips in 2000. In 2004, Sun and HP introduced their first dual core CPUs.

The first dual core chips for x86-based PCs and servers were introduced in 2005 and included the Pentium D and Pentium Processor Extreme Edition 840 from Intel and the Opteron 800 and Athlon 64 X2 from AMD. A year later, Intel added dual cores to its Itanium line.

Increased Performance - Similar Power Consumption
Because the continual increase in single core clock speeds were using more and more power and generating excessive heat, dual cores were developed to expand performance without more heat. Dual core systems may use the same or a little bit more energy, but achieve approximately an 80% increase in processing power over single core CPU chips.

For Everybody
Dual-core chips are not just for advanced applications; rather, everyday tasks can take advantage of two simultaneous processing streams. For example, routine downloads of e-mail and software updates that increasingly take place in the background no longer slow down the foreground application. Virus scans and backup programs can be initiated without interfering with the primary task.

CPUs with two or more cores are expected to gain significant momentum in the 2007-2010 time frame, not only in servers, but in desktop and laptop computers as well. See multicore, triple core, quad core, dual processor, Pentium D, Pentium Processor Extreme Edition, Core 2 and core.