The release ships nine JEPs, and two of them touch you whether you opt in or not. G1 is now the default collector in every environment (JEP 523), and object headers shrink from 96 bits to 64 (JEP 534), which trims heap footprint and helps data locality with no flag to set. The security headline is JEP 527: ML-KEM hybrid key exchange for TLS 1.3, tracking NIST's FIPS 203, with nothing to wire up. Round out the list with the usual previews — structured concurrency reaches its seventh, primitive patterns their fifth — plus JFR in-process redaction that scrubs secrets from flight recordings before they leave the process. Worth being clear on support, because the number invites confusion: 27 is not an LTS. It carries six months of updates, and the next long-term release is JDK 29, a year out. If you're pinned to 25 or 21 for the post-quantum work, Oracle says the same TLS hardening backports over the coming year — 25 by October's Critical Patch Update, the older lines through 2027. So treat 27 as the place to try the post-quantum path in earnest, not the place to ship it on a long-lived service.