File I/O and working with JSON

Always open files with with — it closes the file automatically, even if an error happens partway through:

with open("notes.txt", "w") as f:
    f.write("Hello, file!")

with open("notes.txt", "r") as f:
    contents = f.read()

JSON is the most common structured format you'll read and write:

import json

data = {"name": "Ada", "courses": ["Python", "SQL"]}

with open("data.json", "w") as f:
    json.dump(data, f)

with open("data.json") as f:
    loaded = json.load(f)