Essential Python Basics: 25 Key Concepts Every Developer Should Know

Python is an interpreted, interactive, object‑oriented high‑level programming language known for its readability and concise syntax.

1) What is Python? What are its advantages?

Python offers objects, modules, threads, exception handling, automatic memory management, a simple and extensible syntax, many built‑in data structures, and is open source.

2) What is PEP8?

PEP8 is a style guide that provides recommendations to improve code readability.

3) What are pickling and unpickling?

The pickle module serializes any Python object to a string and writes it to a file (pickling); the reverse process restores the original object (unpickling).

4) How is Python interpreted?

Python source code is executed directly; the interpreter converts it to intermediate code, then to machine code for execution.

5) How does Python manage memory?

Memory is managed in a private heap accessible only to the interpreter, with a built‑in garbage collector that frees unused objects.

6) Which tools help with debugging or static analysis?

PyChecker and Pylint are static analysis tools that report errors, code complexity, and style violations.

7) What are Python decorators?

Decorators are a language feature that simplify modifying functions.

8) Difference between arrays and tuples?

Arrays are mutable, while tuples are immutable and can be used as dictionary keys.

9) How are arguments passed by value or reference?

All variables are references to objects; immutable objects cannot be changed, but mutable objects can be modified.

10) What are dictionary and list comprehensions?

They are concise syntactic constructs for creating dictionaries and lists.

11) Built‑in data structures in Python

Python provides mutable structures (arrays, sets, dictionaries) and immutable structures (strings, tuples, numbers).

12) What is a namespace?

A namespace is a container that holds name‑object mappings, similar to a box where each name points to an object.

13) What is a lambda in Python?

A lambda is an anonymous function defined with a single expression.

14) Why does lambda have no statements?

Because it is designed to create a function object at runtime and return it.

15) What does the pass statement do?

pass

is a null operation used as a placeholder in complex statements.

16) What is an iterator?

An iterator traverses elements of a container such as a list.

17) What is unittest ?

unittest

is Python’s unit‑testing framework supporting test discovery, automation, and grouping.

18) What is slicing?

Slicing extracts a subsequence from ordered types like lists, tuples, or strings.

19) What are generators?

Generators implement iterators using the yield expression.

20) What is a docstring?

A docstring provides documentation for functions, modules, and classes.

21) How to copy an object?

Use copy.copy() for shallow copies or copy.deepcopy() for deep copies, though not all objects are copyable.

22) What are negative indices?

Negative indices count from the end of a sequence (‑1 is the last element, ‑2 the second‑last).

23) How to convert a number to a string?

Use str(); for octal or hexadecimal, use oct() or hex().

24) Difference between xrange and range ?

xrange

returns an xrange object that generates numbers on demand, while range creates a list; xrange uses constant memory.

25) What are modules and packages?

A module is a single Python file; a package is a directory containing multiple modules and sub‑packages.