What is the primary purpose of indentation in Python?

The primary purpose of indentation in Python is to define the structure and scope of loops and functions. Python uses indentation to indicate code blocks, which are necessary for defining the boundaries of control structures such as loops (for and while) and function definitions. This means that the code inside a loop or function must be uniformly indented to be recognized as part of that loop or function. Proper indentation not only makes the code readable but also is syntactically required to avoid errors. In contrast, other languages may use curly braces or other markers to define blocks of code, but in Python, indentation is essential to its design and functionality.

The concept of commenting out lines of code refers to using specific symbols to ignore certain lines during execution, which is not related to indentation. Indentation does not inherently increase the speed of the program, as it serves more as a structural guideline rather than influencing execution speed. Lastly, creating new data types is a separate topic in Python that does not involve indentation as a mechanical necessity. Therefore, the correct understanding of Python's reliance on indentation significantly enhances one’s ability to write functional and organized code.