Python Keywords: Understanding Reserved Words

 

In Python, keywords are reserved words that have predefined meanings and purposes. They are part of the language's syntax and cannot be used as identifiers (like variable names, function names, or class names). Think of them as instructions that tell the Python interpreter what to do. Python has a relatively small number of keywords compared to some other languages.

Why are keywords important?

• Define Syntax: They form the fundamental building blocks of Python code.
• Control Flow: Many keywords control the flow of execution (e.g., if, else, for, while).
• Define Structures: Some keywords define structures like classes and functions.
• Prevent Conflicts: Reserving these words prevents you from accidentally using them in a way that would confuse the interpreter.

Here's a description of several common Python keywords, in English:

• and: A logical operator that returns True if both operands are True. Example: if x > 0 and y < 10:
• as: Used to create an alias (a different name) for a module when importing it. Example: import math as m
• assert: Used for debugging. It tests a condition and raises an AssertionError if the condition is false. Example: assert x > 0, "x must be positive"
• break: Used to exit a loop prematurely (e.g., for or while loop). Example: for i in range(10): if i == 5: break
• class: Used to define a class, which is a blueprint for creating objects. Example: class MyClass:
• continue: Used to skip the rest of the current iteration of a loop and proceed to the next iteration. Example: for i in range(10): if i % 2 == 0: continue
• def: Used to define a function. Example: def my_function():
• del: Used to delete an object or variable. Example: del my_variable
• elif: Short for "else if." Used in conditional statements to check multiple conditions. Example: if x > 0: ... elif x < 0: ... else:
• else: Used in conditional statements to execute a block of code if the if condition is false. Example: if x > 0: ... else:
• except: Used in try...except blocks to handle exceptions (errors). Example: try: ... except ValueError:
• False: A boolean value representing logical falsehood.
• finally: Used in try...except blocks to execute a block of code regardless of whether an exception occurred. Example: try: ... except: ... finally:
• for: Used to create a loop that iterates over a sequence (e.g., a list, tuple, or string). Example: for i in my_list:
• from: Used to import specific attributes from a module. Example: from math import sqrt
• global: Used to declare a variable as global, meaning it can be accessed from anywhere in the program.
• if: Used to create a conditional statement. Example: if x > 0:
• import: Used to import a module. Example: import math
• in: Used to check if a value is present in a sequence. Example: if x in my_list:
• is: Used to check if two variables refer to the same object in memory.
• lambda: Used to create an anonymous function (a function without a name).
• None: Represents the absence of a value.
• nonlocal: Used to declare a variable as nonlocal, meaning it's not local to the current function but belongs to an enclosing function.
• not: A logical operator that negates a boolean value. Example: if not x > 0:
• or: A logical operator that returns True if at least one operand is True. Example: if x > 0 or y < 10:
• pass: A null statement that does nothing. It's often used as a placeholder. Example: if x > 0: pass
• raise: Used to raise an exception. Example: raise ValueError("Invalid input")
• return: Used to return a value from a function. Example: return x + y
• True: A boolean value representing logical truth.
• try: Used to enclose a block of code that might raise an exception. Example: try: ... except:
• while: Used to create a loop that continues as long as a condition is true. Example: while x > 0:
• with: Used to manage resources (e.g., files) in a safe and convenient way. Example: with open("file.txt", "r") as f:
• yield: Used to create a generator function.

You can find a complete list of Python keywords and their descriptions in the official Python documentation: https://docs.python.org/3/keywords.html