The Pentium 4 is a seventh-generation x86 architecture microprocessor produced by Intel and is their first all-new CPU design, called the NetBurst architecture, since the Pentium Pro of 1995. Unlike the Pentium II, Pentium III, and various Celerons, the architecture owed little to the Pentium Pro/P6 design, and was new from the ground up. The microarchitecture of Netburst featured a very deep instruction pipeline, with the intention of scaling to very high frequencies. It also introduced the SSE2 instruction set for faster SIMD integer, and 64-bit floating-point computation. Later Pentium 4 models introduced new technological advances such as Hyper-Threading, a feature to make one physical CPU appear as two logical and virtual CPUs.

The original Pentium 4, codenamed "Willamette", ran at 1.4 and 1.5 GHz and was released in November 2000 on the Socket 423 platform, and later Socket 478 from 1.5GHz to 2GHz. Notable with the introduction of the Pentium 4 was the comparatively fast 400 MT/s FSB. It was actually based on a 100 MHz clock wave, but the bus was quad-pumped, meaning that the maximum transfer rate was four times that of a normal bus, so it was considered to run at 400 MT/s. The AMD Athlon was running at 266 MT/s (using a double-pumped bus) at that time.
As is traditional with Intel's flagship chips, the Pentium 4 also came in a low-end Celeron version (often referred to as Celeron 4) and a high-end Xeon version intended for SMP configurations. Nearly 6 years after the introduction of the original Pentium 4 CPUs, a dual core version, called the Pentium D, was released.