Do Python dictionaries preserve insertion order?

Yes. Since Python 3.7 the language guarantees that dictionaries remember the order in which keys were inserted, and iteration over keys, values, or items follows that order. This was an implementation detail in 3.6 and became an official guarantee in 3.7. Updating an existing key does not change its position; only deleting and re-inserting moves it to the end.

What is the difference between get and indexing a dict?

d[key] raises KeyError when the key is missing, while d.get(key) returns None (or a supplied default) instead of raising. Use indexing when a missing key is a genuine error, and get when absence is expected and you want a fallback. get never inserts the key; for that behavior use setdefault.

What does setdefault do?

setdefault(key, default) returns the value for key if it exists; otherwise it inserts key with the given default and returns that default. It is handy for building dictionaries of lists, like d.setdefault(k, []).append(v), which creates the list on first use. Unlike get, it mutates the dictionary when the key is absent.

What are dict view objects?

keys(), values(), and items() return dynamic view objects, not lists. A view reflects later changes to the dictionary and supports iteration and length, and key/item views also support set operations like intersection and difference. To get a static list, wrap the view in list(). Iterating a view while modifying the dict raises a RuntimeError.

Is this the complete list of dict methods?

Yes. Python's dict has a fixed set of methods — get, setdefault, update, pop, popitem, clear, copy, keys, values, items, and the classmethod fromkeys — all listed here. Merge operators like the pipe operator added in 3.9 are noted. For exact version availability consult the official Python documentation's Mapping Types page.

Python Dict Methods Reference

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Python’s dict is a mutable mapping that, since 3.7, preserves insertion order. Its methods cover safe lookup, defaults, merging, removal, and the dynamic view objects returned by keys, values, and items. This is a searchable offline reference.

How it works

Each method lists its signature, return value, and behavior:

Lookup — get(key, default) returns a default instead of raising; indexing d[key] raises KeyError.
Defaults — setdefault(key, default) returns the value, inserting the default if the key is absent.
Merge — update(other) writes another mapping’s pairs in; the | operator (3.9+) returns a merged dict.
Removal — pop(key[, default]) removes and returns a value; popitem() removes and returns the last inserted pair (LIFO since 3.7).
Views — keys(), values(), items() return live views reflecting later changes; wrap in list(...) for a snapshot.

Example

Group values into lists with setdefault:

groups = {}
for name, team in members:
    groups.setdefault(team, []).append(name)

Notes

Insertion order is guaranteed since Python 3.7; popitem() removes the last-inserted pair.
View objects are dynamic — they track changes to the dict. Iterating a view while mutating the dict raises RuntimeError.
fromkeys(keys, value) is a classmethod; beware passing a mutable default — all keys share the same object.
This reference covers all standard dict methods.