What is `pubspec.yaml` and what role does it play in a Flutter project?

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pubspec.yaml is the central project manifest — it tells Flutter what dependencies to fetch, what assets to bundle, what fonts to ship, and what Dart/Flutter SDK versions you require. Sections: name , description , version ( 1.0.0+42 — semver + buildNumber). environment — Dart SDK + Flutter SDK constraints. dependencies — runtime packages (pub.dev, Git, local path). dev_dependencies — build-time tools (tests, lints, build_runner , freezed ) — never shipped in the binary. flutter: — assets, fonts, uses-material-design , etc. Version syntax: ^1.2.3 = >=1.2.3 <2.0.0 (caret, most common); ~1.2.3 = >=1.2.3 <1.3.0 ; pinning exact versions causes transitive lockup. Three details senior interviewers listen for: (1) **`^1.2.3` means `>=1.2.3 <2.0.0`** — the caret is the most common syntax and signals you've read pubspec semantics; (2) **`dev_dependencies` is for tools that don't ship in the binary** (test, lints, build_runner) — pinning them keeps your runtime bundle clean; (3) **`version: 1.0.0+1`** — the `+1` is the *build number*, separate from the semver, used by app stores. Add: assets and fonts are declared here too (common gotcha).