Glossary
Register
A small, ultra-fast storage location built directly into the CPU, used to hold operands, addresses, and CPU state during execution.
A register is a named storage cell inside the CPU itself — orders of magnitude faster than RAM. On x86-64, general-purpose registers include RAX, RBX, RCX, RDX, RSI, RDI, RSP (stack pointer), and RBP (frame pointer). Special registers like RIP (instruction pointer) and RFLAGS (condition flags) control program flow. Calling conventions define which registers pass function arguments and which the callee must preserve. When debugging, watching register values is often the fastest way to track data through a function.