Top 100+ Python Interview Questions & Answers

Python has become one of the most popular programming languages in the world, thanks to its simplicity, versatility, and ease of use. It is used for a wide range of applications, from web development to data analysis and machine learning. Python developers are in high demand, and if you are looking to land a job in this field, it is important to be well-prepared for your interview.

Basic Python Questions

1. What is Python?
Python is an interpreted, high-level programming language that is used for a wide range of applications, including web development, data analysis, and machine learning. It was created by Guido van Rossum in 1991.
2. What are the applications of Python?
Python can be used for web development, data analysis and visualization, scientific computing, machine learning, artificial intelligence, automation and scripting, game development, and more.
3. What is the difference between Python 2 and Python 3?
Python 2 is no longer supported, while Python 3 is the current version. Python 3 is more efficient and has better syntax.
4. What are the different data types in Python?
Python supports a wide range of data types, including integers, floats, strings, lists, tuples, dictionaries, and sets.
5. How do you declare a variable in Python?
In Python, you can declare a variable by assigning a value to it. For example, x = 5.
6. What is the difference between a list and a tuple in Python?
A list is a mutable data type, which means that it can be modified after it is created. A tuple, on the other hand, is immutable, which means that it cannot be modified after it is created.
7. What is a dictionary in Python?
A dictionary is a data type in Python that allows you to store key-value pairs. Each key in the dictionary must be unique.
8. How do you comment in Python?
In Python, you can comment a line of code by adding a hash symbol (#) before it. For example, # This is a comment.
9. What is PEP 8?
PEP 8 is a set of coding conventions for Python code. It covers topics such as indentation, variable naming, and line length.
10. What is a module in Python?
A module is a file containing Python code that can be imported and used in other Python files. Modules can contain functions, classes, and variables.
11. What are the advantages of using Python?
Python is known for its simplicity, readability, and ease of use. It is also highly versatile, with a wide range of applications. Python is easy to learn and use, has a large community, has a vast collection of libraries and frameworks, and can be used in multiple domains.
12. What are the disadvantages of using Python?
Python can be slower than other programming languages, such as C++, because it is interpreted rather than compiled. It can also be difficult to maintain large code bases in Python.
13. Python is Programming or Scripting language?
Python can be used for both programming and scripting. It is a high-level programming language that allows you to write programs for a variety of applications, including web development, scientific computing, and automation. It can also be used as a scripting language to automate tasks, manipulate data, and perform other simple operations. The ability to use Python for both programming and scripting makes it a versatile language that can be used in a wide range of applications.
14. What are the built-in data types available in Python?
The built-in types available in Python are Integer, Float, Boolean, String, List, Tuple, Dictionary, Set, Frozenset, Byte, Bytearray, NoneType.

Intermediate Python Questions

1. What is object-oriented programming?
Object-oriented programming is a programming paradigm that is based on the concept of objects. Objects are instances of classes, which are templates for creating objects. Object-oriented programming allows for code reuse, encapsulation, and abstraction.
2. What is a class in Python?
A class is a template for creating objects. It contains data (attributes) and functions (methods) that define the behaviour of the objects.
3. What is inheritance in Python?
Inheritance is a mechanism in object-oriented programming that allows you to create a new class based on an existing class. The new class inherits the attributes and methods of the existing class.
4. What is polymorphism in Python?
Polymorphism is a concept in object-oriented programming that allows you to use a single interface to represent multiple types of objects. This can be achieved through inheritance and method overriding.
5. What is the difference between a method and a function in Python?
A method is a function that is defined within a class and is called on an object of that class. A function, on the other hand, can be defined outside of a class and can be called independently.
6. What is the difference between a shallow copy and a deep copy in Python?
A shallow copy of an object in Python creates a new object that references the same memory location as the original object. A deep copy, on the other hand, creates a completely new object with its own memory location.
7. What is the difference between a generator and a list comprehension in Python?
A generator is an iterator that generates values on the fly, rather than creating a list of values all at once like a list comprehension does.
8. What is a decorator in Python?
A decorator is a function that takes another function as input and returns a new function that adds some kind of functionality to the original function.
9. What is a lambda function in Python?
A lambda function is an anonymous function that can be defined on a single line of code. It is often used for simple operations and can be passed as an argument to another function.
10. What is a virtual environment in Python?
A virtual environment is a self-contained directory that contains its own Python installation, packages, and dependencies. It is used to isolate projects and prevent conflicts between different versions of packages.
11. What is a closure in Python?
A closure is a function that remembers the values in the enclosing scope, even if they are not passed as arguments. It can be used to create functions with persistent data.
12. What is a Namespace in Python?
A namespace is a container that holds a set of identifiers (variables, functions, classes, etc.) and maps them to their corresponding objects. A namespace can be thought of as a dictionary that maps names to objects.
Python has 4 types of namespaces. Those are
Built-in namespace: This namespace contains built-in functions, keywords, and exceptions that are available in Python by default.
Global namespace: This namespace contains variables and functions that are defined at the module level and are accessible throughout the module.
Local namespace: This namespace contains variables and functions that are defined inside a function and are only accessible within that function.
Class namespace: This namespace contains the attributes of a class, including its methods and data members.
13. What is an iterator in Python?
An iterator is an object that allows us to traverse a container or collection of data, such as a list, tuple, or dictionary. An iterator provides a way to access the elements of a collection sequentially, without exposing its internal representation.
To create an iterator in Python, we can use the built-in iter() function, which returns an iterator object for a given iterable. We can then use the next() function to retrieve the next element of the iterator. The iterator raises a StopIteration exception when there are no more elements to retrieve.
14. What is slicing in Python?
Slicing is a technique in Python that allows us to extract a portion of a sequence (such as a string, list, or tuple) by specifying a start index, an end index, and a step size.

Advanced Python Questions

1. What is multithreading in Python?
Multithreading is a way of running multiple threads of execution in a single process. In Python, this can be achieved using the threading module.
2. What is multiprocessing in Python?
Multiprocessing is a way of running multiple processes in parallel to increase performance. In Python, this can be achieved using the multiprocessing module.
3. What is a context manager in Python?
A context manager is a Python object that defines the methods enter() and exit(). It is used to manage resources, such as files, that need to be cleaned up after use.
4. What is the Global Interpreter Lock (GIL) in Python?
The Global Interpreter Lock is a mechanism in Python that ensures that only one thread can execute Python bytecode at a time. This can limit the performance of multithreaded Python programs.
5. What is a coroutine in Python?
A coroutine is a type of function that allows for cooperative multitasking. It can be paused and resumed at specific points, allowing for more efficient use of system resources.
6. What is the asyncio module in Python?
The asyncio module is a library in Python that allows for asynchronous programming. It provides a way of running concurrent code without the need for multiple threads.
7. What is the difference between pickling and unpickling in Python?
Pickling is the process of converting a Python object into a stream of bytes that can be saved to a file or sent over a network. Unpickling is the process of converting the byte stream back into a Python object.
8. What is the difference between a list and a set in Python?
A list is an ordered collection of values that can contain duplicates, while a set is an unordered collection of unique values.
9. What is the difference between a static method and a class method in Python?
A static method is a method that is bound to a class, rather than an instance of the class. It can be called without creating an object of the class. A class method, on the other hand, is a method that is bound to the class itself, rather than an instance of the class.
10. What is monkey patching in Python?
Monkey patching is the process of modifying code at runtime, either by replacing existing code or by adding new code. It is a powerful technique but can be dangerous if not used carefully.

Python Web Frameworks Questions

1. What is a web framework in Python?
A web framework in Python is a collection of libraries, tools, and APIs that are used to develop web applications.
2. What are the popular web frameworks in Python?
The popular web frameworks in Python include Django, Flask, Pyramid, and Bottle.
3. What is Flask?
Flask is a lightweight micro web framework in Python that is used to build and develop small to medium-sized web applications.
4. What is Django?
Django is a full-stack web framework in Python that is used to develop large-scale web applications.
5. What is Pyramid?
Pyramid is a flexible web framework in Python that is used to develop web applications of any size.
6. What is Bottle?
Bottle is a minimalist web framework in Python that is used to develop small web applications.
7. What is WSGI?
WSGI stands for Web Server Gateway Interface. It is a standard interface between web servers and web applications written in Python.
8. What is middleware in Flask?
Middleware in Flask is a function that can intercept and modify requests and responses in a Flask application.
9. What is Jinja2?
Jinja2 is a templating engine in Python that is used to generate HTML, XML, and other markup languages.
10. What is a Flask blueprint?
A Flask blueprint is a way to organize Flask applications into smaller and reusable components.

Python Data Science Questions

1. What is NumPy?
NumPy is a library in Python that is used for numerical computing. It provides support for large, multi-dimensional arrays and matrices, as well as functions for mathematical operations on these arrays.
2. What is Pandas?
Pandas is a library in Python that is used for data manipulation and analysis. It provides support for data structures like Data Frames and Series, as well as functions for data cleaning, merging, and grouping.
3. What is Matplotlib?
Matplotlib is a library in Python that is used for data visualization. It provides support for creating various types of plots, including line plots, scatter plots, and histograms.
4. What is Scikit-Learn?
Scikit-Learn is a library in Python that is used for machine learning. It provides support for various algorithms like linear regression, decision trees, and k-nearest neighbours.
5. What is TensorFlow?
TensorFlow is an open-source machine learning library in Python that is used for building and training neural networks.
6. What is a confusion matrix?
A confusion matrix is a table that is used to evaluate the performance of a machine learning model. It shows the number of true positives, false positives, true negatives, and false negatives.
7. What is overfitting?
Overfitting is a problem in machine learning where a model is too complex and fits the training data too well. This can lead to poor performance on new, unseen data.
8. What is underfitting?
Underfitting is a problem in machine learning where a model is too simple and does not fit the training data well enough. This can also lead to poor performance on new, unseen data.
9. What is cross-validation?
Cross-validation is a technique in machine learning that is used to evaluate the performance of a model. It involves splitting the data into training and testing sets multiple times and averaging the results.
10. What is regularization?
Regularization is a technique in machine learning that is used to prevent over-fitting. It involves adding a penalty term to the cost function to discourage large weights.

Python Object-Oriented Programming(OOP) Questions

1. What is object-oriented programming?
Object-oriented programming is a programming paradigm that is based on the concept of objects. An object is an instance of a class, which is a blueprint for creating objects.
2. What is a class in Python?
A class in Python is a blueprint for creating objects. It defines the attributes and methods of the objects that will be created from it.
3. What is an object in Python?
An object in Python is an instance of a class. It has its own set of attributes and methods that are defined by the class.
4. What is inheritance in Python?
Inheritance in Python is a way to create a new class by deriving from an existing class. The new class inherits the attributes and methods of the existing class.
5. What is polymorphism in Python?
Polymorphism in Python is a concept where objects of different classes can be treated as if they were objects of the same class. This is achieved through method overriding and method overloading.
6. What is encapsulation in Python?
Encapsulation in Python is a concept where the attributes and methods of a class are hidden from outside access. They can only be accessed through the methods of the class.
7. What is a constructor in Python?
A constructor in Python is a special method that is called when an object of a class is created. It is used to initialize the attributes of the object.
8. What is a destructor in Python?
A destructor in Python is a special method that is called when an object of a class is destroyed. It is used to free up any resources that were used by the object.
9. What is method overloading in Python?
Method overloading in Python is a concept where a class has multiple methods with the same name, but different parameters.
10. What is method overriding in Python?
Method overriding in Python is a concept where a subclass provides a different implementation for a method that is already defined in its parent class.

Python Web Development Questions

1. What is Django?
Django is a high-level Python web framework that is used for rapid development of web applications.
2. What is WSGI?
WSGI (Web Server Gateway Interface) is a specification in Python that defines how web servers communicate with web applications.
3. What is a virtual environment in Python?
A virtual environment in Python is a way to create an isolated environment for a project. It allows different projects to use different versions of Python packages without conflicts.
4. What is a decorator in Python?
A decorator in Python is a function that is used to modify the behaviour of another function. It is a powerful tool for adding functionality to existing functions.
5. What is a RESTful API?
A RESTful API is an API (Application Programming Interface) that follows the principles of Representational State Transfer (REST). It uses HTTP requests to access and manipulate resources.
6. What is AJAX?
AJAX (Asynchronous JavaScript and XML) is a technique in web development that allows web pages to be updated asynchronously without reloading the entire page.
6. What is JSON?
JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write and easy for machines to parse and generate.
8. What is a template engine in Python?
A template engine in Python is a tool that is used to generate dynamic HTML pages. It allows for the separation of presentation and logic.
9. What is SQLAlchemy?
SQLAlchemy is a library in Python that is used for working with databases. It provides support for various database engines and ORM (Object Relational Mapping) features.

Tips for a Successful Interview

It is important to note that while knowing the answers to these questions is helpful, it is also important to have a strong understanding of the fundamentals of Python and be able to apply that knowledge to solve real-world problems.

Preparing for a Python interview can seem daunting, but with enough practice and preparation, it is possible to ace the interview and land the job. Some tips for preparing for a Python interview include:

1. Practice coding exercises and problems to build your skills and confidence.
2. Review the basics of Python, including syntax and data structures.
3. Familiarize yourself with common Python libraries and frameworks.
4. Brush up on computer science concepts, such as algorithms and data structures.
5. Be prepared to discuss your experience and projects you have worked on.

Advice for a Successful Interview

Finally, being well-versed in Python is becoming increasingly important in the tech industry. Familiarizing yourself with the most frequently asked interview questions and practicing your skills can help you stand out from other candidates and land your dream job. In addition to technical knowledge, it is also important to demonstrate good communication skills during the interview. Employers want to see that you can explain complex concepts in a clear and concise manner, and that you can work well in a team environment.

Conclusion:
The 100+ most frequently asked interview questions helps you to building your skills and knowledge. And also demonstrating good communication skills, you can increase your chances of landing a Python-related job. Therefore, it is recommended to prepare thoroughly and practice coding exercises to ace your Python interview. Remember to also ask questions during the interview to show your interest in the company and the position. This can help you gain a better understanding of the company culture, expectations, and potential opportunities for growth.

All the best! and Good luck in your Python interview!