In Python, variables are essential tools for storing and manipulating data in your programs. By using variables, you can assign names to values, making your code easier to understand and manage. These names, known as identifiers, can also be used for modules and functions, enhancing the readability and maintainability of your code.

Creating Variables

In Python, you don’t need a special command to create a variable. A variable is created the moment you assign a value to it. Here are some examples:

a = 10 b = "Hello World!" print(a)    # 10 will be printed print(b)    # “Hello World!” will be printed

 

Naming Variables

There are specific rules for naming variables in Python:

• A variable name must begin with a letter or an underscore (_).
• A variable name cannot start with a number.
• A variable name can only contain letters, numbers, and underscores (A-Z, a-z, 0-9, and _).
• Variable names are case-sensitive, meaning height, Height, and HEIGHT are all different variables.
• Variable names cannot be Python keywords.

Here are some examples of valid variable names:

x temperature abc apple _temp123 _abc_cde_123

 

In Python, variables are used to store data that can be manipulated and referenced throughout a program. Variables play a pivotal role by allowing us to assign names to values, making code easier to understand and manage. These names, known as identifiers, can be applied not only to variables but also to modules and functions, enhancing readability and maintainability of the code.

Python does not have a specific command to declare a variable. A variable comes into existence as soon as you assign a value to it for the first time. 

Case Sensitivity

In Python, identifiers are case-sensitive. This means that apple, Apple, aPple, and APPLE are all different variables. While you have a lot of freedom in naming variables, it's best to choose names that clearly indicate the variable’s purpose or use.

Reserved Words

Python has a set of reserved words, or keywords, that are used by the language itself and cannot be used as variable names. These keywords are integral to Python's syntax and functionality. Here are some examples of Python keywords:

• False
• class
• return
• while

Here is a list of Python keywords:

Table 2-1. Python Keywords

None	break	except	in	raise
False	await	else	import	pass
and	continue	for	lambda	try
True	class	finally	is	return
as	def	from	nonlocal	while
asnyc	elif	if	not	with
assert	del	global	or	yield

 

Best Practices for Variable Naming

Although it’s possible to use the names of Python’s built-in functions (like print()) as variable names, this is strongly discouraged. Doing so can lead to confusion and errors, as it overwrites the built-in functionality, which can cause unexpected results.

Here are some tips for naming variables:

• Use meaningful names that describe what the variable represents.
• Avoid using single letters or generic names unless they are for temporary or loop variables.
• Stick to lowercase letters and underscores for variable names (this is called snake_case).
• Avoid using Python keywords as variable names to prevent conflicts.

By following these guidelines and best practices, you can write clear, readable, and error-free Python programs.