Wikipedia Reference Information
x86 or 80x86 is the generic name of a microprocessor architecture, first developed and manufactured by Intel.
The architecture has twice been extended to a larger word size. In 1985, Intel released the 32-bit 386 to replace the 16-bit 286. This extension to the x86 architecture is commonly called IA-32 (an abbreviation for Intel Architecture, 32-bit), but is also referred to as i386, x86-32, or simply Intel Architecture.
In 2003, AMD further extended the architecture to 64 bits, variously called x86-64, AMD64 (AMD's branding), Intel 64 (Intel's branding, formerly EM64T or IA-32e) and x64 (Microsoft and Sun Microsystems' vendor-neutral naming convention). Intel 64 should not be confused with the unrelated IA-64 architecture.
The complete, up-to-date and editable article about x86 can be found at Wikipedia: x86