Worpress theme for startups.
Wordpress Theme Development Library https://codex.wordpress.org/Theme_Development
Wordpress Coding Standards https://make.wordpress.org/core/handbook/best-practices/coding-standards/
Theme Unit Testing https://codex.wordpress.org/Theme_Unit_Test
Wordpress CLI https://wp-cli.org/
Wordpress Developer Resources | Documentation
https://developer.wordpress.com/docs/