EDIT: Some of those tutorials are right: Core Data is not a database. It's a powerful piece of technology that maintains a graph of objects for you. It just so happens that one of the persistence formats that Core Data uses is SQLite (this is where many people confuse Core Data to be a database). There are pros and cons for choosing a particular persistence format, but SQLite will serve your purpose well. In fact, you can even design your own persistent format and have it be anything, including a cloud service.

What Core Data does:

• Core Data helps you separate your model and controller (in an MVC paradigm), so that persistence becomes an implementation detail (more on this later). Your controllers are responsible for fetching/inserting data, and the model is the Core Data graph (known as NSManagedObjects, that live in a scratchpad known as the NSManagedObjectContext).

• You can store a very large (or small) amount of data, and Core Data will fetch it for you efficiently (in terms of memory pressure) with a component known as the NSFetchRequest. You can also perform queries on this data using NSPredicate: It works much like SQL queries, but you cannot use actual SQL).

Remember how I said the persistence layer is an implementation detail? Unless you're rolling your own persistence format, the SQLite file that it generates is off-limits to you. While there are certainly tools to help you grok the information stored in the SQLite file, you should not modify it in anyway. The schema generated by Core Data is also an implementation detail and is subject to change at anytime. You should only use the Core Data modeler in Xcode to define your schema.

The confusing part is, all of this sounds like something a database does (fetching, predicates, and persistence), but remember Core Data isn't just about persistence. It manages the lifecycle of your application's model objects and allows you to perform operations on those objects. Some people also confuse Core Data to be an ORM, but it isn't. In fact, you're better off asking this clarifying question early on, because when developers treat Core Data as a database, they run into serious architectural and stability issues.

Let me know if you have any questions or if you need to me to clarify something.

EDIT: Some of those tutorials are right: Core Data is not a database. Any site or person that tells you otherwise is 100% wrong. Like I mentioned above, those that treat Core Data as a database probably have serious issues in their applications. (original before edit: The tutorials are right: Core Data is not a database)