As we continue evolving our front-end projects and building increasingly dynamic user interfaces, React remains one of the most essential tools in our development toolkit. Its component-based architecture gives us the flexibility to design reusable, scalable code, while its modern features push us to think differently about how we structure and manage logic.

In this post, we’re taking a closer look at a few foundational React concepts that often spark debate and learning moments: the difference between Functional and Class Components, how state plays a central role in interactivity, and what the component lifecycle means in a modern React application.

What is React?

React is a JavaScript library for building user interfaces, created by Facebook. It allows us to build reusable UI components and handle dynamic content efficiently.

With the release of React 16.8, we gained Hooks, which brought major changes to how we write components – especially with Functional Components.

Functional vs Class Components

React supports two main ways to create components:

1. Class Components

These are ES6 classes that extend from React.Component and can hold state and lifecycle methods.

import React, { Component } from 'react';

class Welcome extends Component {
  constructor(props) {
    super(props);
    this.state = {
      message: 'Hello from Class Component!'
    };
  }

  render() {
    return <h1>{this.state.message}</h1>;
  }
}

export default Welcome;

2. Functional Components

Originally, these were stateless functions. But now, with React Hooks, they can manage state and side effects.

Functional Components are preferred for most cases due to their simplicity, better readability, and compatibility with Hooks.

import React, { useState } from 'react';

function Welcome() {
  const [message, setMessage] = useState('Hello from Functional Component!');

  return <h1>{message}</h1>;
}

export default Welcome;

Understanding State in React

State lets us create components that are dynamic and interactive. It’s like a component’s personal memory.

In a Class Component:

this.state = {
  count: 0
};

this.setState({ count: this.state.count + 1 });

In a Functional Component using useState:

const [count, setCount] = useState(0);

setCount(count + 1);

Component Lifecycle

Lifecycle methods are only available in Class Components. They allow us to hook into different phases of a component’s life.

Lifecycle Phases:

1. Mounting – Component is being created and inserted.
2. Updating – Component is re-rendering due to state or props changes.
3. Unmounting – Component is being removed.

Common Lifecycle Methods:

componentDidMount() {
  // Called after the component is mounted
}

componentDidUpdate(prevProps, prevState) {
  // Called after updates
}

componentWillUnmount() {
  // Called just before the component is removed
}

Functional Components: useEffect Hook

React Hooks give us useEffect to replicate lifecycle behavior.

import React, { useEffect } from 'react';

function Example() {
  useEffect(() => {
    console.log('Component mounted');

    return () => {
      console.log('Component will unmount');
    };
  }, []);

  return <div>Lifecycle in Functional Component</div>;
}

Conclusion

As we build modern applications with React, understanding the fundamentals isn’t just helpful—it’s essential. Knowing the difference between Functional and Class Components gives us historical context and practical insight into how React has matured. More importantly, grasping how state works and how component lifecycle events behave empowers us to write more predictable, efficient, and maintainable code.