What are the main principles to consider when developing quality code?

Principles of developing quality code:

• Readability — code should be understandable by other developers, using clear variable and function names.
• Simplicity — avoid unnecessary complexity, write the minimal necessary code.
• Reusability — use functions and modules to avoid duplication.
• Testability — write code that can be easily covered with tests.
• Documentation — comment on complex sections and use documentation.
• Adherence to standards — follow coding style and best practices.

For example, in Python, it is important to follow PEP8 for style and write functions with a single responsibility.