The React JS component life cycle is an important concept to understand when developing applications with React. It consists of four distinct phases, which each have specific methods and events which can be used to trigger particular behaviour within a component. 

The following are the three phases: 
● Mounting: The first phase is the “Mounting” phase in which the component is initialized and inserted into the DOM (Document Object Model). During this stage, lifecycle methods such as constructor(), render() and component Did Mount() are called. 
● Updating: After mounting, components enter the second phase known as “Updating” during which state changes or user interactions cause updates to occur on a UI element. The component's shouldComponentUpdate, componentDidUpdate, and render methods are called during this phase. 
● Unmounting: The phase where a component is removed from the DOM is Unmounting. The component's componentWillUnmount method is called during this phase. 
Finally, after all these stages have been completed successfully then reacts re-render process begins again – starting at step one! All of these processes combined form what we know today as the React JS Component Life Cycle - making it easier for developers to create complex web apps quickly without sacrificing quality or performance! 

The main lifecycle methods are 
● constructor(props): The constructor method is called before the component is mounted. It is used to initialize the component's state and to bind event handlers. 
● componentDidMount(): The componentDidMount method is called after the component is mounted and rendered. It is used to perform side effects such as fetching data or subscribing to a service. 
● shouldComponentUpdate(nextProps, nextState): The shouldComponentUpdate method is called before the component updates. It allows you to prevent unnecessary re-renders by returning false. 
● componentDidUpdate(prevProps, prevState): The componentDidUpdate method is called after the component has been updated. It is used to perform side effects such as fetching new data or updating service. 
● componentWillUnmount(): The componentWillUnmount method is called before the component is unmounted. It is used to perform cleanup tasks such as unsubscribing from a service.