In YAML, maps and lists are two fundamental data structures — basically key/value pairs vs ordered sequences.

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📌 1. Map = Key → Value pairs (like a dictionary in Python, object in JSON) • Keys are unique • Values can be strings, numbers, booleans, lists, or even other maps • Order usually doesn’t matter (though YAML preserves it, semantics treat it as unordered)

Example:

person: name: Alice age: 30 city: Paris

Equivalent in JSON:

{ “person”: { “name”: “Alice”, “age”: 30, “city”: “Paris” } }

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📌 2. List = Ordered sequence of items (like an array in JSON, list in Python) • Items are defined with a - dash • Order matters • Items can be strings, numbers, maps, or nested lists

Example:

fruits:

  • apple
  • banana
  • cherry

Equivalent in JSON:

{ “fruits”: [“apple”, “banana”, “cherry”] }

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📌 3. Combined Example

YAML lets you nest maps inside lists and vice versa:

users:

  • name: Alice role: admin
  • name: Bob role: user

Here: • users is a list • Each list item is a map with name and role keys

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✅ Quick Difference Table

Feature Map List Structure Key → Value pairs Ordered items Uniqueness Keys must be unique Items can repeat Order Not semantically important Important Access by Key name Index number

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