Which one is created first? Database or Instance? Forgive me I just learned Oracle. There exist so many terminologies in the Oracle world. 

Regarding the concept of database and instance. I already know some differences between them. 

The Oracle database includes all the physical files belonging to the server while the Oracle instance will provide the interface between the user and the data he wants to manipulate. 

But I want to know which one is created first? 

I had thought the database should be created first, before the instance. But after I read this post Creating a Database with the CREATE DATABASE Statement I think I am. 

Because the manual shows theses instructions:

Step 5: (Windows Only) Create an Instance 
Step 9: Issue the CREATE DATABASE Statement 

Please help me to clarify it.
Introduction to the Oracle Database Instance

A database instance is a set of memory structures that manage database
files. A database is a set of physical files on disk created by the
CREATE DATABASE statement. The instance manages its associated data
and serves the users of the database.
Every running Oracle database is associated with at least one Oracle
database instance. Because an instance exists in memory and a database
exists on disk, an instance can exist without a database and a
database can exist without an instance.

A database can exist without an instance, but to use that database, you need to start an instance, then mount and open the database in it.
You can &quot;create&quot; a database by simply copying the files of an existing database. You do not need an instance for that. But to use that database, you need an instance.
If you want to create a database from scratch, you need a running instance first.