Node.js Module Resolution: How require() Finds the Right File

Short summary

This tutorial explains how Node.js resolves modules when require() is called, classifying them into core, local, and third-party categories. Core modules like fs and http are built into the runtime and load instantly without filesystem lookups. Local modules are project files resolved via relative paths, while third-party modules are found in node_modules. The article walks through the resolution decision tree with simple examples.

• •Node.js classifies require() targets as core, local, or third-party modules
• •Core modules load directly from the runtime with no filesystem search
• •Module resolution converts a string into an actual file path before execution

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