There are many ways to merge dictionaries in Python. Python 3.9 introduced a new syntax for merging dictionaries.

You can now merge dictionaries by using the merge operator |. From all the possible options, using the merge operator is probably the fastest and cleanest way to achieve this goal.

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d1 = {'name': 'Tom', 'age': 23}
d2 = {'country': 'France', 'city': 'Paris'}

details = d1 | d2

print(details)
# {'name': 'Tom', 'age': 23, 'country': 'France', 'city': 'Paris'}

If you don’t want to reassign the dictionaries, you can use |= operator to get the second dictionary to merge into the first one.

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d1 = {'name': 'Tom', 'age': 23}
d2 = {'country': 'France', 'city': 'Paris'}

d1 |= d2

print(d1)
# {'name': 'Tom', 'age': 23, 'country': 'France', 'city': 'Paris'}
What if two dictionaries have a shared key?
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d1 = {'name': 'Tom', 'age': 23}
# name key appears again but with different value
d2 = {'country': 'France', 'name': 'Michael'}

details = d1 | d2

print(details)
# {'name': 'Michael', 'age': 23, 'country': 'France'}

If an overlap exists, Python will overwrite the left dictionary with the value of the keys of the right dictionary. This is important to remember. Should you prefer to keep the values of the first dictionary, reverse the order in which you merge the dictionaries.