Just because the Node.js applications run on a single processor, they don’t take advantage of a multiple-core system by default. Clustering is used to overcome this issue. The cluster mode is used to start up multiple node.js processes, thereby having multiple instances of the event loop. When we start using clusters in a Node.js app, it creates multiple node.js processes. But there is also a parent process called the cluster manager, which is responsible for monitoring the health of the individual instances of the application.