x86_64 ASM refers to assembly language instructions specific to the 64-bit version of the x86 architecture, commonly found in modern CPUs. Assembly language is a low-level programming language that provides direct control over hardware through symbolic instructions. x86_64, also known as AMD64 or Intel 64, extends the original 32-bit x86 instruction set to support 64-bit processing, enabling access to larger memory spaces and improved performance. In cybersecurity, understanding x86_64 ASM is crucial for tasks such as malware analysis, reverse engineering, and exploit development, as many operating systems and applications run on this architecture. Mastery of x86_64 ASM allows security professionals to analyze binary code, identify vulnerabilities, and develop effective defenses.