When it comes to building web applications with Python, Flask is one of the most popular frameworks you’ll come across. It’s lightweight, flexible, and easy to use, making it an excellent choice for beginners who want to dip their toes into web development. In this Flask Tutorial for Beginners, we’ll walk you through everything you need to know to create your very first web application, even if you have little to no prior experience.
What is Flask?
Flask is a micro web framework for Python, designed to be simple and easy to get started with. Unlike other full-stack frameworks, Flask doesn’t come with everything bundled in. Instead, it provides the core essentials to run a web app, while giving you the freedom to add extensions only when you need them.
Some reasons developers love Flask include:
Lightweight: You only install what you need.
Beginner-friendly: Its syntax is clean and easy to follow.
Flexible: Works well for small projects and can scale up with extensions.
Great documentation: Flask has an active community and resources to help you learn.
If you’re a beginner in web development, starting with Flask is like learning how to ride a bicycle before driving a car—it gives you all the basics without overwhelming you.
Setting Up Your Environment
Before diving into coding, let’s make sure your system is ready for Flask development.
Step 1: Install Python
Flask runs on Python, so make sure you have Python 3.x installed. You can download it from python.org
.
To check if Python is installed, run this in your terminal or command prompt:
python --version
Step 2: Create a Virtual Environment
Using a virtual environment is a good practice to manage dependencies for your projects.
python -m venv venv
Activate it:
On Windows:
venv\Scripts\activate
On Mac/Linux:
source venv/bin/activate
Step 3: Install Flask
Once your virtual environment is active, install Flask using pip:
pip install Flask
That’s it—you’re ready to build your first app!
Creating Your First Flask App
Let’s build a very simple web application step by step.
Step 1: Create a Python File
Create a file called app.py in your project folder.
Step 2: Add Basic Flask Code
from flask import Flask
app = Flask(name)
@app.route('/')
def home():
return "Hello, Flask!"
if name == 'main':
app.run(debug=True)
Step 3: Run Your App
In your terminal, run:
python app.py
You’ll see something like this:
- Running on http://127.0.0.1:5000/
Open that URL in your browser, and you’ll see Hello, Flask! displayed. Congratulations—you’ve just created your first Flask web application!
Understanding the Code
Let’s break down what just happened:
from flask import Flask – imports the Flask library.
app = Flask(name) – creates a Flask application instance.
@app.route('/') – defines the route (the URL path) for your homepage.
def home(): – the function that returns content to display on the homepage.
app.run(debug=True) – starts the server, with debug mode enabled to auto-reload changes.
This simple structure is the backbone of every Flask app.
Adding More Routes
One of the best things about Flask is how easily you can add new pages (routes).
@app.route('/about')
def about():
return "This is the About Page"
Now, if you go to http://127.0.0.1:5000/about, you’ll see your About Page.
You can add as many routes as you need—Flask makes it simple.
Returning HTML Templates
Returning plain text is fine for practice, but real applications need HTML templates. Flask uses Jinja2 for templating, which allows you to write HTML files with placeholders for dynamic content.
Step 1: Create a templates Folder
Inside your project folder, create a folder named templates.
Step 2: Add an HTML File
Create a file called index.html inside templates:
<!DOCTYPE html>
Flask App
Welcome to My First Flask App
This page is powered by Flask!
Step 3: Update Your Python Code
from flask import Flask, render_template
app = Flask(name)
@app.route('/')
def home():
return render_template('index.html')
if name == 'main':
app.run(debug=True)
Now, when you open your homepage, you’ll see your HTML content rendered beautifully.
Handling User Input with Forms
Let’s add a simple form to take user input.
Step 1: Create form.html inside templates:
<!DOCTYPE html>
User Form
Enter Your Name
Step 2: Update app.py:
from flask import Flask, render_template, request
app = Flask(name)
@app.route('/form', methods=['GET', 'POST'])
def form():
if request.method == 'POST':
name = request.form['username']
return f"Hello, {name}!"
return render_template('form.html')
if name == 'main':
app.run(debug=True)
Now, visit /form, enter your name, and Flask will greet you personally.
Why Choose Flask?
By now, you’ve seen how quick and easy it is to build applications with Flask. Here’s why developers keep using it:
Great for learning – Perfect if you’re just starting out.
Flexible – Add extensions for authentication, databases, APIs, and more.
Lightweight – Minimal setup means faster development.
Scalable – You can start small and grow your app as needed.
Flask is widely used by startups, learners, and even big companies who prefer flexibility over rigid frameworks.
Next Steps in Your Flask Journey
Now that you’ve built your first application, here are some topics you can explore to level up:
Connecting a Database – Use SQLite or SQLAlchemy with Flask.
Authentication & Authorization – Add login and signup features.
REST APIs – Learn to build APIs using Flask for mobile and frontend apps.
Deploying Flask Apps – Host your application on platforms like Heroku, AWS, or PythonAnywhere.
Using Flask Extensions – Explore tools like Flask-WTF (forms), Flask-Login (authentication), and Flask-Mail (email).
Conclusion
In this beginner-friendly Flask tutorial, you learned how to set up Flask, create routes, use templates, and handle forms. With just a few lines of Python, you built a working web application. The beauty of Flask lies in its simplicity—it gives you the essential tools to start building while allowing endless flexibility as your projects grow.
Whether you’re a student learning Python, a hobbyist building fun projects, or an aspiring developer preparing for real-world applications, Flask is the perfect starting point. Keep experimenting, explore more advanced features, and before you know it, you’ll be building full-fledged web apps.
If this flask tutorial helped you, share it with others and start building your own projects today!
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