Question

I’ve been looking at Groovy on Grails and noticed a line at the bottom that says:

Grails aims to bring the “coding by convention” paradigm to Groovy.

What exactly is coding by convention?

Answer 1

Convention over Configuration (aka Coding by convention) is a software design paradigm which seeks to decrease the number of decisions that developers need to make, gaining simplicity, but not necessarily losing flexibility.

The phrase essentially means a developer only needs to specify unconventional aspects of the application. For example, if there’s a class Sale in the model, the corresponding table in the database is called sales by default. It is only if one deviates from this convention, such as calling the table "products_sold", that one needs to write code regarding these names.

When the convention implemented by the tool you are using matches your desired behavior, you enjoy the benefits without having to write configuration files. When your desired behavior deviates from the implemented convention, then you configure your desired behavior.

From "Convention over configuration" article on Wikipedia.