It’s one of the features of Entity Framework. Entity framework introduces Code First along with Database First & Model First.
Now let’s discuss what is the approach of the code first? Code First modeling workflow aims a database that doesn’t exist and Code First will create it.
Basically, In Database First Developer first creates a database design. In the Database, the design developer creates the table, table relation, implementation of data & creates store procedure.
But in the case of Code First there is no need to create database design, the developer will just work with their code and code first will add new tables accordingly. It can also use the empty database. Code First will create the new database (if it does not exists) and map the classes with the database using default Code first conventions.
The code first is mainly ideal for domain-driven design. In the Code-First approach, the main focus on the domain of the application and start creating classes for the domain entity instead of design the database first and then form the classes which counterpart the database design.
The following figure demonstrates the code-first approach.
Capture 1

The following figure demonstrates the code-first migration workflow:
Capture 2

We, NOI Software currently is using this framework to generate our work on the new web application.