How to Create and Start a basic flask app

To create a basic Flask app, follow these steps:

1. Install pip flask

Imports the Flask class from the Flask module, allowing us to create a Flask-based web application

Then, install Flask using pip (Python package manager) by running the following command in your terminal or command

2. Import Flask

In the file, import the Flask class from the flask package:

It imports the Flask class from the Flask module, enabling the creation of a web application based on Flask.

#pip install Flask

from flask import Flask

3. Create flask app

Creating a Flask app (application) involves several essential steps. Flask, a lightweight Python web framework, facilitates rapid and efficient web application development.

In this example, I will provide you with the foundational structure for a Flask application that you can further customize to meet your specific project requirements.

app = Flask(__name__)

The __name__ parameter represents the name of the current Python module. It helps Flask determine the root path of the application.

Flask is a class provided by the Flask framework for building web applications.

__name__ is a special Python variable that represents the name of the current module. When you create a Flask application, you typically pass __name__ as an argument to the Flask class.

This is important because Flask uses this value to determine the root path of your application.

4. Define a route and a view function

A route is a URL path that users can visit in their browser. You define routes using Python decorators. A view function is associated with each route and returns the content that should be displayed to the user

Establishes an instance of the Flask web application.

Read: How to Create a SignUp Page using Flask

Defines a route (in this case, ‘/’) and an associated function (hello_world) responsible for handling this route.

When a user accesses the root URL (‘/’), the application responds with the message “Hello, World!” Initiates the application when the script is executed directly, with debugging capabilities enabled.

def hello_world():
    return 'Hello, World!'

5. Run the Flask app

At the end of your file, add the following code to run the Flask development server

if __name__ == '__main__':

The debug=True parameter enables the debug mode, which provides helpful error messages during development

How to Create and Start a basic flask app

6. Create full code in flask app

Below is a revised version of the text that explains how the provided code allows us to run a basic web application and serve it like a website

“With this code, we can create and host a simple web application, effectively serving it as a fully functional website. The provided code enables us to deploy a basic web application, which can be accessed through a web browser just like any other website.

By running this code, we set up a server that responds to incoming requests, allowing users to interact with our web application by visiting its URL.

This seamless process allows the web app to be available online, providing an interactive and user-friendly experience akin to browsing any regular website.”

#pip install Flask

from flask import Flask          # import flask

app = Flask(__name__)

def hello_world():
    return 'Hello, World!'

if __name__ == '__main__':

7. Start the Development Server and running or

Open a terminal or command prompt, navigate to the directory where your file is located, and run the following command


You should see output indicating that the Flask development server is running. By default, the server will be available at

Open your web browser and navigate to, and you should see the “Hello, World!” message.

The application is initiated when the script is executed directly, and debugging capabilities are enabled. This allows for real-time debugging and error tracking during development.

In summary, this code sets up a Flask web application, defines a route for the root URL, and provides a simple “Hello, World!” response. Additionally, it allows for debugging when the script is run directly, facilitating a smoother development process.

"Hello, World

Read: How to Create a Login Page Using in flask

Hello friends, My name is Satish Kumar Pal. I am as a Data Scientist and Python developer with 2+ years of broad-based experience in building data-intensive applications ,overcoming complex architectural and scalability issues in diverse industries. Proficient in predictive modeling, data processing and data mining algorithms as well as scripting languages including python. capable of creating , developing, testing and deploying.

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