Itanium (/aɪˈteɪniəm/ eye-TAY-nee-əm) is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture (formerly called IA-64). Intel markets the processors for enterprise servers and high-performance computing systems. The architecture originated at Hewlett-Packard (HP), and was later jointly developed by HP and Intel.

The Itanium architecture is based on explicit instruction-level parallelism, in which the compiler decides which instructions to execute in parallel. This contrasts with other superscalar architectures, which depend on the processor to manage instruction dependencies at runtime. In all Itanium models, up to and including Tukwila, cores execute up to six instructions per clock cycle. The first Itanium processor, codenamed Merced, was released in 2001.

Itanium-based systems have been produced by HP (the HP Integrity Servers line) and several other manufacturers. As of 2008, Itanium was the fourth-most deployed microprocessor architecture for enterprise-class systems, behind x86-64, IBM POWER, and SPARC. The most recent processor, Tukwila, originally planned for release in 2007, was released on February 8, 2010.

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