Oracle Database 18c (18.3) has officially been released for download on Linux x86-64. See KM Doc 742060.1 for more details on the release schedule for other platforms.
This is the first version of the database to follow the new yearly release model. Read KM Doc 2285040.1 for more details. For practical purposes, you can think of Oracle Database 18c as a Patchset of the Oracle Database 12c release. However, instead of being named “Oracle Database 12c Release 2 126.96.36.199”, the new naming structure reflects the year in which the product released.
Oracle Database 18c contains a lot of small, but extremely useful incremental improvements, most of which focus on the three key marquee features in Oracle Database 12c Release 2: