Understanding Python Variables: Names, Assignment, and Values

In Python, a variable stores a piece of data and consists of three parts: the variable name, the assignment operator, and the variable value.

"Variables are composed of three parts"

The typical structure can be illustrated as name = "Mike" , where name is the variable name, = is the assignment operator, and "Mike" is the variable value.

What is a variable name?

A variable name acts as the address of the memory space allocated for the variable value, allowing the program to locate and retrieve the stored data.

Variable naming rules

Do not use pinyin or Chinese characters.

Avoid Python reserved keywords.

The name cannot start with a digit.

Variable naming conventions

There are three common styles:

Lowercase with numbers and underscores (snake_case) – the most widely used.

CamelCase – each word starts with a capital letter.

All uppercase – typically used for constants.

Assignment operator

The equal sign ( = ) binds the right‑hand value to the left‑hand variable name, enabling the name to reference the value.

Variable value

The value represents the actual state of the data. When a value’s reference count drops to zero, Python’s garbage collector reclaims the memory.

Important variable properties

Each variable has three key attributes:

id : the unique memory address of the value, viewable with id() .

type : the data type of the value, viewable with type() .

value : the actual data stored.

Example

An example problem: calculate a student's average score from three subjects, display the average with one decimal place, and show the percentage of the Chinese score relative to the total.

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