x86_64)

A 64-bit instruction set architecture (ISA) that expands x86 registers and memory addressing while maintaining full backward compatibility.

Originally launched by AMD as AMD64 in 2003, x86_64 serves as the standard 64-bit instruction set for modern desktop and server CPUs. It expands the legacy 32-bit x86 architecture by doubling the number of general-purpose registers to 16 and increasing their width to 64 bits (using prefixes like RAX and RDI). This evolution removes the 4 GB memory ceiling of 32-bit systems: it supports a theoretical limit of 16 exabytes of RAM. Most implementations utilize a 48-bit or 52-bit virtual address space to handle current enterprise workloads. The architecture remains the backbone of global computing by maintaining native compatibility with legacy 16-bit and 32-bit software through its versatile Long Mode execution state.

https://en.wikipedia.org/wiki/X86-64