Java 26 introduces a range of improvements spanning performance, security, and language features. Key highlights include: restrictions on reflective modification of final fields to strengthen encapsulation; removal of the long-deprecated Applet API; AOT object caching now available with any garbage collector including ZGC; HTTP/3 support in the HTTP Client API via QUIC; G1 GC throughput improvements reducing thread synchronization overhead; a second preview of PEM encoding APIs for cryptographic objects; sixth preview of Structured Concurrency; second preview of Lazy Constants for faster startup; eleventh incubator of the Vector API for SIMD-based computation; and a fourth preview extending pattern matching to primitive types in instanceof and switch.