Package extensions are a new feature for packages available in Julia 1.9. It aims to solve the problem where you might be reluctant to take on a package as a dependency just to extend a function to a type in that package due to e.g. increased load time of the package.
The Julia release process is important since it's the process by which all the work that goes into the Julia language gets delivered to users.
This talk details the various steps that are made to ensure that Julia releases are of high quality with few regressions, both in correctness and performance.