What is Core Data?

Core Data is a framework that you use to manage the model layer objects in your application. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence.

https://developer.apple.com/library/tvos/documentation/Cocoa/Conceptual/CoreData/index.html#//apple_ref/doc/uid/TP40001075-CH2-SW1

Core Data is an object graph and persistence framework provided by Apple in the Mac OS Xand iOS operating systems. It was introduced in Mac OS X 10.4 Tiger and iOS with iPhone SDK 3.0.^[1] It allows data organised by the relational entity–attribute model to be serialisedinto XML, binary, or SQLite stores. The data can be manipulated using higher level objects representing entities and their relationships. Core Data manages the serialised version, providing object lifecycle and object graph management, including persistence. Core Data interfaces directly with SQLite, insulating the developer from the underlying SQL.^[2]

Just as Cocoa Bindings handle many of the duties of the controller in a model–view–controller design, Core Data handles many of the duties of the data model. Among other tasks, it handles change management, serializing to disk, memory footprint minimization, and queries against the data.

https://en.wikipedia.org/wiki/Core_Data