Todo list application. In this application, I implemented all the fundamental concepts of ReactJS such as Components, state, props, JSX, events, LifeCycle, Router. I used ‘React.Fragments’ which is a common pattern in React is for a component to return multiple elements. Fragments let you group a list of children without adding extra nodes to the DOM. I have a place wherein I am required to use npm uuid package for generating unique Id's uuid.v4(). After installing uuid package. But this is just a front end and usually I need to have ‘Third party API’ or my own server where you make a request to ‘REST API’ later on, my next move in this application is to create HTTP requests. For this purpose I used ‘Axios’, a library for HTTP requests. Axios just fetches data of JSONPlaceholder instead of writing hard code. I just make the Array inside the state empty and used LifeCycle (Component Did mount) to render that data which is fetched by Axios also i just limit the array of JSONPlaceholder. So your question would be that what is the ‘JSONPlaceholder’? It is a free online REST API that you can use whenever you need some fake data.It's great for tutorials, testing new libraries, sharing code examples. Your next question would be why and where i used functional and class components ?