Microservices is a game changing architectural pattern , for developing large scale enterprise applications, which makes easier the tasks of build and maintenance when they are broken down into independent, autonomous, modular, self-contained components which work together. Each component is developed separately, and the application is then simply the sum of its constituent components. This is in contrast to a traditional, “monolithic” application which is all developed all as a single component.
There are many reasons why this approach is considered an easier way to develop large applications, particular enterprise applications, and various types of software as a service delivered over the Internet.
One of the reasons is from a project engineering perspective. When the different components of an application are separated, they can be developed concurrently. Another is resilience. Rather than relying upon a single virtual or physical machine, components can be spread around multiple severs or even multiple data centers. If a component dies, you spin up another, and the rest of the application can continue to function. It allows more efficient scaling, as rather than scaling up with bigger and more powerful machines, or just more copies of the entire application, you can scale out with duplicate copies of the heaviest-used parts.