In his post, Martin Fowler talks about Strangler Figs
They seed in the upper branches of a tree and gradually work their way down the tree until they root in the soil. Over many years they grow into fantastic and beautiful shapes, meanwhile strangling and killing the tree that was their host.https://martinfowler.com/bliki/StranglerFigApplication.html
This gives a definition to a prevalent development pattern when you are working on moving an existing monolith application to a new microservices-based cloud-native application. You do not make the change in one go, but instead, start small, take a part or functionality from the application, move it to a newer cloud-native microservice, and then remove that piece from the existing application. Step by step the old application is completely replaced by a fresh cloud native microservice-based application.
There will be three phases to such a transition
Transform: Create a parallel application build in microservices, cloud-native design.
Coexist: Incrementally you will implement features and transfer traffic from older monolithic applications to newly built cloud-native applications.
Eliminate: Completely remove the older version and only maintain the new application.https://www.amazon.in/Cloud-Native-Applications-Jakarta-Microservices-ebook/dp/B093D2QMF8