When it comes to WordPress design and development, there is a certain set of rules called the coding standards that you must follow while creating your website.
These include best practices that you should follow to make your website more accessible and standardized. Your website will still work even if you don’t follow these coding standards and best practices. But, it is highly recommended that you follow them so that your code meets the web standards and is accessible by everyone.
According to the WordPress Core Contributor Handbook, the purpose of having WordPress Coding Standards is to create a baseline for collaboration and review within various aspects of the WordPress open source project and community from core code to themes and plugins.