Major new features of the 3.10 series, compared to 3.9
Among the new major new features and changes so far:
PEP 623 -- Deprecate and prepare for the removal of the wstr member in PyUnicodeObject.
PEP 604 -- Allow writing union types as X | Y
PEP 612 -- Parameter Specification Variables
PEP 626 -- Precise line numbers for debugging and other tools.
PEP 618 -- Add Optional Length-Checking To zip.
bpo-12782: Parenthesized context managers are now officially allowed.
PEP 632 -- Deprecate distutils module.
PEP 613 -- Explicit Type Aliases
PEP 634 -- Structural Pattern Matching: Specification
PEP 635 -- Structural Pattern Matching: Motivation and Rationale
PEP 636 -- Structural Pattern Matching: Tutorial
PEP 644 -- Require OpenSSL 1.1.1 or newer
PEP 624 -- Remove Py_UNICODE encoder APIs
PEP 597 -- Add optional EncodingWarning
bpo-38605: from future import annotations (PEP 563) used to be on this list in previous pre-releases but it has been postponed to Python 3.11 due to some compatibility concerns. You can read the Steering Council communication about it here to learn more.
bpo-44828: A change in the newly released macOS 12 Monterey caused file open and save windows in IDLE and other tkinter applications to be unusable. As of 2021-11-03, the macOS 64-bit universal2 installer file for this release was updated to include a fix in the third-party Tk library for this problem. All other files are unchanged from the original 3.10.0 installer. If you have already installed 3.10.0 from here and encounter this problem on macOS 12 Monterey, download and run the updated installer linked below.