React is built on one simple but powerful idea:
Break the UI into small, reusable components.
Everything in React is a component.
Buttons
Navbars
Cards
Forms
Pages
Entire app sections
To master React, you MUST understand components deeply.
But beginners often get confused between Functional Components vs Class Components, their roles, differences, lifecycles, and how React treats them internally.
This blog gives you the clearest, simplest, and most beginner-friendly explanation you will ever read—no code, only concepts.
A React component is a self-contained, reusable piece of UI.
You can think of a component as:
A small building block
A piece of UI
A function that returns structure
A logical unit that handles its own content and state
Each component has:
A visual structure (UI)
A behavior (what it does)
Optional state (data)
Optional props (external data)
React apps are built by combining many such components.
Originally, React introduced Class Components first.
Later, developers realized that writing logic inside classes felt heavy, complex, and difficult to reuse.
So React introduced Functional Components + Hooks, making component logic much simpler.
Today:
Functional Components are the modern standard
Class Components are legacy but still important to understand
React supports both, but most new apps use functional components exclusively.
Functional components are simply JavaScript functions that:
Accept input (props)
Return UI
Use hooks for state and lifecycle
They are short
Easy to read
Easy to write
No complex syntax
No binding
No "this" keyword confusion
Hooks make them extremely powerful
Functional components became the default choice after hooks were introduced.
Class components were React's original method for handling:
State
Lifecycle
Events
Complex logic
They were powerful but had drawbacks:
Verbose syntax
Confusing "this" keyword
Long lifecycle methods
Harder to reuse logic
More boilerplate
Functional components + hooks replaced most class-based patterns.
Still, class components remain in millions of existing projects—so understanding them is essential.
Lightweight
Much shorter
Pure functions
Logic and UI together
Hooks manage lifecycle
Heavy syntax
Requires a class definition
Must use "this" keyword
Lifecycle methods are separate
State inside a class object
Functional components feel modern.
Class components feel traditional and complex.
Hooks like:
useState
useEffect
useRef
useContext
useReducer
These hooks allow functional components to handle modern application logic like:
Data updates
Side effects
Global state
Async behavior
Performance optimization
Class components store state inside a single object.
Updates happen using setState, which merges changes.
Functional: modern, minimal, powerful
Class: older, heavier, more complex
A component has a lifecycle:
Created
Updated
Rendered
Removed
This happens in both types of components, but differently.
Functional components don't have lifecycle methods.
Instead, lifecycle behavior comes from:
useEffect (runs after render)
Cleanup functions (remove effects)
Multiple effects for different responsibilities
Hooks offer a more flexible and intuitive way of handling lifecycle events.
Class components have explicit lifecycle methods such as:
componentDidMount
componentDidUpdate
componentWillUnmount
These methods run at different phases of the component lifecycle.
You often write multiple, unrelated logics inside one large method, making code messy.
Hooks fixed this problem by allowing:
One hook per responsibility
Cleaner, more maintainable code.
Props are the same in both components:
They represent external data
Passed from parent to child
Read-only
Used to customize components
But how they are accessed differs.
Props come directly as function arguments.
Props come through this.props.
Again, functional components are cleaner.
One of the biggest advantages of functional components is reusable logic.
You can extract any logic and create your own custom hook for reuse.
Examples:
Authentication hook
Fetching hook
Form validation hook
Theme hook
These can be shared across many components.
To reuse logic in class components, you needed:
Higher-order components
Render props
Complex patterns
Hooks completely simplified this process.
Functional components are generally more performance-friendly because:
They are simple functions
They avoid heavy class instantiation
Hooks run efficiently
React optimizes them better
Class components require more overhead.
Internally, React treats:
Functional components as pure render functions
Class components as instances with lifecycle methods
React Fiber (the engine) handles both, but functional components map better to:
Interruptible rendering
Concurrent mode
Time slicing
React's future optimizations
This is one reason React encourages functional components.
Class components require binding event handlers, which confuses beginners.
Functional components simply define functions.
No binding.
No "this".
Less mental load.
Functional components win easily.
Fewer lines
Simpler logic
Hooks separate logic
Easy to test
Easy for beginners
Larger files
Harder to follow
Mixed logic in lifecycle methods
More mental overhead
Teams building large apps prefer functional components because they reduce complexity.
React's development team is clear:
Functional components + Hooks are the recommended modern approach.
Class components are still supported, but they are no longer evolving.
Easy
Modern
Widely used
Required for real-world development
Important for interviews
Essential for maintaining older apps
Helps understand React's evolution
You should know both but functional components should be your foundation.
React wanted to solve major problems:
Complex lifecycle
Confusing state logic
Bloated class syntax
Unnecessary boilerplate
Difficult reusability
Performance limitations
Hooks elegantly solved them all.
This is why React calls functional components:
"The future-proof way to write React."
Building modern apps
Using hooks
Needing reusable logic
Working with teams
Maintaining clean structure
Using advanced React features
Working on legacy codebases
Maintaining older apps
Handling outdated libraries
Following older tutorials
| Feature | Functional Components | Class Components |
|---|---|---|
| Syntax | Simple function | Requires class |
| State | Hooks | setState |
| Lifecycle | useEffect | Lifecycle methods |
| Logic reuse | Custom hooks | Hard |
| Binding | Not needed | Required |
| Performance | Better | Heavy |
| Readability | Very high | Moderate |
| Future-proof | Yes | No |
| Recommended | Yes | Only for legacy |
Functional components win in almost every category.
React Fiber treats:
As pure functions
No instance created
Hooks map to fiber nodes
Easy to pause and resume
Easy for concurrent rendering
Require component instance creation
Maintain lifecycle management
Harder to optimize
Less flexible for future React features
Understanding this explains why React's future is functional.
Knowing both:
Helps in interviews
Helps maintain older code
Gives deeper understanding of React's evolution
Makes you more versatile
Makes debugging easier
Helps you contribute to any React codebase
Both component types played important roles in React's journey, but today:
Functional Components + Hooks are the modern, powerful way to build React apps.
They offer:
Cleaner code
Simpler logic
Better reusability
Improved performance
Future compatibility
Easier learning curve
Class components are still useful to understand, especially when working with legacy systems but they are no longer the recommended way to build modern React apps.
If you're a beginner, start with functional components.
If you want to become a complete developer, master both.
Yes, in older apps and tutorials but new projects prefer functional components.
Yes for interviews and legacy code, but functional should be your focus.
Functional components are generally faster due to hooks and Fiber optimization.
To simplify component logic, remove class complexity, and improve reusability.
Yes. Hooks provide more control and flexibility than lifecycle methods.
No- they will stay supported, but new features target functional components.
To master React components and build modern applications, consider enrolling in our comprehensive React JS Training program. For those looking to become complete developers, we also offer specialized Full Stack Java Developer Training that includes React along with backend technologies.
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