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

Code Example:

❌ Invalid ----

True = 5

Output:

-----

ERROR!

Traceback (most recent call last):

File "<main.py>", line 1

True = 5

^^^^

SyntaxError: cannot assign to True

Rule 6: Avoid using Python's built-in names as variable names.

Python may not throw an error when you do this, but your variable can shadow the built-in name, which may change the behavior of your code or cause errors later.

Constants: True, False, None, Ellipsis, NotImplemented

Exceptions / Warnings: ArithmeticError, AssertionError, AttributeError, BaseException, BaseExceptionGroup, BlockingIOError, BrokenPipeError, BufferError, BytesWarning, ChildProcessError, ConnectionAbortedError, ConnectionError, ConnectionRefusedError, ConnectionResetError, DeprecationWarning, EOFError, EncodingWarning, EnvironmentError, Exception, ExceptionGroup, FileExistsError, FileNotFoundError, FloatingPointError, FutureWarning, GeneratorExit, IOError, ImportError, ImportWarning, IndentationError, IndexError, InterruptedError, IsADirectoryError, KeyError, KeyboardInterrupt, LookupError, MemoryError, ModuleNotFoundError, NameError, NotADirectoryError, NotImplementedError, OSError, OverflowError, PendingDeprecationWarning, PermissionError, ProcessLookupError, RecursionError, ReferenceError, ResourceWarning, RuntimeError, RuntimeWarning, StopAsyncIteration, StopIteration, SyntaxError, SyntaxWarning, SystemError, SystemExit, TabError, TimeoutError, TypeError, UnboundLocalError, UnicodeDecodeError, UnicodeEncodeError, UnicodeError, UnicodeTranslateError, UnicodeWarning, UserWarning, ValueError, Warning, ZeroDivisionError

Built-in Functions: abs, aiter, all, anext, any, ascii, bin, breakpoint, callable, chr, compile, delattr, dir, divmod, enumerate, eval, exec, filter, format, getattr, globals, hasattr, hash, help, hex, id, input, isinstance, issubclass, iter, len, locals, map, max, min, next, oct, open, ord, pow, print, quit, repr, reversed, round, setattr, sorted, sum, vars, zip

Built-in Types / Classes: bool, bytearray, bytes, classmethod, complex, dict, float, frozenset, int, list, memoryview, object, property, range, set, slice, staticmethod, str, super, tuple, type

Special `__...__` Names:__build_class__, __debug__, __doc__, __import__, __loader__, __name__, __package__, __spec__

Code Example:

❌ Invalid ----

print = 5 # This line of code doesn't throw error

print("Hello") # This causes error

Output:

-----

ERROR!

Traceback (most recent call last):

File "<main.py>", line 2, in <module>

TypeError: 'int' object is not callable

3. Variable naming conventions

Naming conventions are recommended ways of naming variables. They help maintain readability, consistency, and good coding practices across your programs. They are not rules, so not following them will generally not cause an error in Python.

Convention 1: Use lowercase names

name = "Alice"

age = 10

score = 95

Convention 2: Use snake_case for multiple words

first_name = "Alice"

student_age = 10

total_score = 95

Convention 3: Use UPPER_CASE for values that are intended to remain unchanged during the execution of the program.

MAX_SCORE = 100

PI = 3.14159

Convention 4: Choose meaningful and descriptive names

student_name = "Alice" # ✅ Clear

sn = "Alice" # 🤔 Less descriptive

# use names that clearly indicate True/False

is_active = True

has_permission = False

can_edit = True

4. Ways of Assigning Values to Variables

Single assignment

One value is assigned to one variable at a time.

name = "Alice"

age = 10

score = 95

Multiple assignment

Multiple variables are assigned their respective values at once.

name, age, score, is_student = "Alice", 10, 95, True

Assigning the same value to multiple variables

x = y = z = 0

Assigning the value of one variable to another variable

a = 10

b = 20

c = a

print(c) # Output: 10

# Swapping values

a, b = b, a

c = a

print(a) # Output: 20

print(b) # Output: 10

print(c) # Output: 20

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