We know that Python programming language can be used to create CLI applications. But, in most cases, CLI applications are used on your local PC.

There are examples when we want to present our calculations or some results in a form that might be suitable for the Internet. To achieve this we need to build a webpage.

In our scenario, we are presenting an example of using Flask and Python script that interacts with our written HTML code. As an option when we can take user data, entered from a webpage, we use WebForms.

There are a few things that you need to think about before you start building your first web app with Flask and Python. First is choosing a suitable Python IDE and build a virtual environment with Flask and Python. Next thing is to see how your Python script will route to the specific resulting  URL. And of course, using Jinja2 templating to use variables that interact with values between Python script and HTML code.

Bellow is our free code example for a basic Web app that calculates Summation or Product of a sequence.