Version 3.15 of the Python programming language has been released. Notable changes in this release include the addition of the sentinel and frozendict built-in types, the use of UTF-8 encoding by default, package start-up configuration files, as well as improvements in the experimental JIT compiler. See the "What's new in Python 3.15" article for an in-depth look at new features in this release, and the changelog for a full list of changes.