Assembly
In plain terms
A human-readable form of a processor's native machine instructions.
Going deeper
Assembly maps almost directly to CPU instructions, giving ultimate control and speed at the cost of being tedious and architecture-specific. It's used where every cycle counts.
Under the hood
You manage registers and memory by hand; it's non-portable across CPU architectures (x86, ARM) and rarely used beyond hot spots and bootloaders.
Examples
Bootloaders, performance-critical kernels, embedded systems, reverse engineering.
Think of it like...
Like writing instructions in the machine's own native tongue, with no translator's convenience.