Below npm 2,036 sits the operating system's package manager, which installed Node.js 2,131 itself, the C libraries that native modules link against, and every tool a Dockerfile needs. On Linux the two you meet most are Debian 319 and Ubuntu 225 's apt, on your servers and in node:24-slim, and Alpine 13,255 's apk, in node:24-alpine. Both work like npm: a registry-like repository, dependency resolution, signed metadata. But they install into one shared system, so each package has exactly one version at a time.