Many notable PyData projects including Jupyter Hub, Matplotlib and JAX follow a versioning scheme called EffVer, where instead of making promises around backward compatibility they communicate the likelihood and magnitude of the work required to adopt a new version.

In this talk we will dive into EffVer, what it is and what it means for developers and users. We will discuss how to apply EffVer to your own projects and how to depend on projects that use it.