How is user data transferred into the system or between systems?

Transferring user data between systems typically involves several steps:

1. Export data from the source system into a convenient format (e.g., JSON, CSV, XML).
2. Transform the data — adapt it to the format and structure suitable for the target system.
3. Import the data into the target system using APIs, scripts, or specialized tools.

In Python, libraries for working with data formats (json, csv, pandas) and API requests (requests) are often used.

Example of simple export and import of JSON:

import json

# Export user data to JSON
user_data = {'id': 123, 'name': 'Ivan', 'email': 'ivan@example.com'}
with open('user_data.json', 'w', encoding='utf-8') as f:
    json.dump(user_data, f, ensure_ascii=False)

# Import data from JSON
with open('user_data.json', 'r', encoding='utf-8') as f:
    imported_data = json.load(f)
print(imported_data)

For complex cases, ETL processes (Extract, Transform, Load) and data migration tools are used.