Infinum WordPress Handbook

Our handbook is based on over 7 years of experience in WordPress development. Here are some numbers behind it:
hours of coding
lines of code
launched projects
WordPress has evolved a lot since its beginnings—from a simple blog CMS to a full-fledged CMS used for a wide range of projects: simple websites, online shops, complex multi-site projects communicating with a wide range of APIs.
As the usage of WordPress in our company increased, we thought it would be a good idea to define a set of style guides for the projects we work on. We try to follow the WordPress Coding Standards for the most part, but, being a software development company working on a wide range of projects, we already use certain coding standards that differ from default WordPress coding standards.