Python is a popular and powerful programming language that is widely used for web development. Flask is a lightweight web framework that allows developers to quickly and easily build web applications in Python. In this tutorial, we will walk through the process of building a simple web application using Python and Flask.

Step 1: Set up the Environment

First, we need to set up our development environment. We will need to install Python and Flask. Open up a command prompt or terminal and type the following command to install Flask:

pip install Flask

Step 2: Create the Application

Create a new Python file called app.py in your working directory. This file will contain the code for our web application.

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello, World!"

if __name__ == "__main__":
    app.run()

In this code, we import the Flask module and create a new Flask application. We define a route for the root URL (“/”) and create a simple “Hello, World!” message to be displayed when the root URL is requested. Finally, we start the Flask application using the app.run() method.

Step 3: Run the Application

To run the application, simply type the following command in your command prompt or terminal:

python app.py

This will start the Flask application and make it available on your local machine at http://localhost:5000/.

Step 4: Test the Application

Open up your web browser and navigate to http://localhost:5000/. You should see the “Hello, World!” message displayed on the page.

Congratulations, you have built a simple web application using Python and Flask! This is just the beginning, there is a lot more you can do with Flask, including adding templates, databases, and more complex routes.