Intel Corporation

Founded by Bob Noyce and Gordon Moore in 1968, both were previously working at Fairchild Semiconductor and left to create their own company. Because there was a hotel chain already named "Moore Noyce" they were forced to come up with another name and decided to use portions of the words integrated electronics, forming Intel.

Until around 1999 Andy Grove was CEO of Intel and helped guide it from the small memory company into the silicon behemoth it is today. Intel was originally making memory and focused on that as their primary money maker. When Busicom requested that they build 12 custom designed chips to put in their calculators they instead decided to make one chip that could handle the jobs of the combined 12. The result was the 4004 Microprocessor and it had computing power equivalent to the vacuum tube ENIAC.

Intel went on to consistently create new and better processors adhering to Moore's Law, created by co-founder and current Chairman Emeritus of the Board Gorden Moore, which stated that processor speeds will continue to double every year and a half. Much of Intel's philosophy and commitment to excellence (at least in the early years) came from former CEO and current Chairman Andy Grove, who joined intel in 1968. Craig Barrett, current CEO, was initially brought in to revolutionize Intel's fabrication technology and procedures, which are now currently unriveled.

Processor History
  First microprocessor built in 1971 for a Japanese calculator company called Busicom. Was never used in a personal PC (which didn't exist yet), but was the first non-custom processor that could be put in many devices.
  Twice the bandwidth of the 4004, used in small electronic devices. It only reached speeds up to 8 megahertz
   First processor for PC. Not popular due to expensive 16-bit bus.
   Cheaper to make because of 8 bit bus. IBM chose this processor of Intel's and unknowingly created a huge partnership.
   Essentially the 8086, but with additional memory space. Created in 1982 it was the first processor with "protected mode" which allowed for virtual memory.
   Full 32-bit bus to memory. EISA and MCA 32-bit I/O buses are introduced, but not accepted widely. It had SX and DX versions with altered internal functionality to make it more profitable. This was the first widely used chip in a CPU and introduced the useful 32 bit protected mode.
   This chip introduced many new features that are today considered fundamental such as onboard cache, a FPU, and pipelining. It also had various versions including SX(no FPU),DX,DX2, and DX4.
   The now famous trademark "Pentium" was first introduced on this chip. Made in 1993, it ran up to 233Mhz. Later the Pentium MMX was introduced. MMX instructions tried to mimmic vector operations in current high-end processors. The MMX or "multimedia" instructions were not implemented efficiently by compilers however they made certain specially optimized applications run much faster.
Pentium Pro
   Completely 32 bit, it was the first processor that did not use old 16 bit technology and it had the capability to be distributed with more than one CPU working together. Made in 1997.
Pentium II
   This chip had expanded cache over the Pentium Pro as well as a faster clock speed (up to 450Mhz), first to use doubling technology with a multiplier. Some Pentium II's with less cache and a slower bus were dubbed "Celeron" and aimed at a lower end market to compete with AMD.
Pentium III
   Faster clock speed reaching up to 1.3Ghz recently, and had new instructions for internet based applications (SSE). The Pentium III also included the controversial CPU number that could identify a processor and also identify a user's computer (it came with the option to disable the number activated). The Xeon version of this chip carried an excessive amount of on die cache and made the chip very expensive, it was targeted towards the server market.
Pentium 4
   A new core architecture with a 20-stage pipeline expected to operate at speeds up to 4Ghz. This chip features new instructions and NetBurst(TM) technology to help the chip perform well on various multimedia applications. This chip featured the much hyped and now much hated Rambus memory, but now supports DDR. Later expanded to support Hyperthreading and the 64 bit extensions to x86 that Intel calls EMT64.
   Code named McKinley, the newest Itanium chip will be dubbed Itanium 2. This chip is the first to implement a new ISA instead of the very old x86. Itanium uses a version of EPIC (Explicitly Parallel Instruction Computing) that they call IA64. These are instructions that are designed to help the processors be run in parallel through ILP (Instruction Level Parallelism). Itanium's architecture is strikingly different from traditional architectures revolving around parallelism with drastically more registers and built in predication and speculation capabilities. The western world's fastest computing network, TeraGrid, is being created using 3,300 Itanium chips.
Xeon / Celeron
   These processors are actually mostly just code names. Intel will change a few minor things in their mainline Pentium brand processor and label them as Celeron or Xeon. Celerons frequently have a slower Front Side Bus and slower clock rate while Xeons have extra cache and multiprocessing features. They are not core processors in themselves but variations on the current Pentium line. ----------------------------

Intel is now a huge multi-billion dollar company with products ranging all over the computer industry. Intel attempts to be a "building block supplier for the internet economy" by providing processors for servers, desktops, and hand-held devices; broadband devices; wireless chips; Intel Play(TM) toys; and various other products.

Advanced Micro Devices (AMD) has fairly recently been providing stiff competition versus Intel, who has had free reign over the desktop PC market for several years. AMD has had various processors including the popular K6,K6-2,Athlon, and Duron and gained a lot of market segment share from Intel by initial going after the "budget" low-end market which Intel had been neglecting.

Intel is now expanding their products to try and gain market share in the non-desktop regions like servers and handhelds. The Itanium and Xeon processors are results of their efforts which have only midly succeeded at this point. Sun, IBM, and until recently the Alpha group in Compaq were the dominating companies and had the most server market share, however Intel has big hopes for its fairly radical new and unproven Itanium architecture.

Various editions and corrections provided by Wicker808
References :