Introduction

Learn what Streamlit is, how it works, and how to build your first app

Streamlit helps you turn Python scripts into interactive web apps without writing HTML, CSS, or JavaScript.

What is Streamlit?

Streamlit is an open-source Python library for building dashboards, data tools, and AI demos. It is especially useful when you want to share a notebook-like workflow with non-technical users.

You can use it to create:

• AI chat interfaces
• Data dashboards
• Simple internal business tools
• Prototype applications for machine learning projects

Streamlit architecture

Streamlit follows a simple client-server model:

1. Your Python script runs on the server.
2. The browser shows the interface.
3. When a user interacts with a widget, the browser sends a new event to the server.
4. Streamlit reruns the script to refresh the page with the latest values.

Execution flow

Streamlit uses a rerun model. Every time a user clicks a button, types in a field, or changes a slider, the script runs again from top to bottom. This makes the app feel reactive and keeps the UI in sync.

import streamlit as st

st.title("Hello Streamlit")
name = st.text_input("Your name")

if name:
    st.write(f"Hello, {name}!")

Creating and running an application

Create a file such as app.py and run it from your terminal:

streamlit run app.py

This starts a local server, usually at http://localhost:8501, and opens your app in the browser.

Project structure

A simple Streamlit project often contains:

• app.py for the main app logic
• data/ for CSV or JSON files
• images/ for local media files
• pages/ for multipage apps

A practical learning path

The Streamlit module is organized into five beginner-friendly sections:

Displaying content

Render text, tables, images, and status messages

User input widgets

Collect text, selections, files, and dates

Layouts and interactivity

Organize your app with sidebars, tabs, and forms

Working with data

Load CSV files, filter rows, and visualize data