In synchronous I/O, the thread (a thread is just a sequence of instructions) will wait till the entire operation is finished. On the other hand, in Asynchronous I/O, the line does not wait during the operations. The operation will run in the background, and it will be called when it is finished. The Asynchronous I/O feature enables an application to have more CPU time available to perform other processing while the I/O is taking place.
LIBUV
LIBUV is another significant dependency on node.js. It gives node.js access to the machine operating system, networking, file system, and more. LIBUV is an open-source library with a strong focus on asynchronous I/O (Input-output). LIBUV is written in C programming language. Apart from focusing on the asynchronous I/O, LIBUV also implements two essential features: event loop and thread pool.
LIBUV is another significant dependency on node.js. It gives node.js access to the machine operating system, networking, file system, and more. LIBUV is an open-source library with a strong focus on asynchronous I/O (Input-output). LIBUV is written in C programming language. Apart from focusing on the asynchronous I/O, LIBUV also implements two essential features: event loop and thread pool.
You should remember that the Event Loop is the heart of Node js, which makes the node completely different from other backend languages.