19c is the last release of the 12.2 code line (12.2 → 18c → 19c). It is the most stable, most deployed Oracle version in production today. If you are running 11g or 12c, 19c is your safe, low-risk upgrade target.
That world is gone.
If you’ve worked with Oracle Database for more than a few years, you remember the old days: a major release every 4–5 years, a few patchsets, and a clear "end of life" you could mark on a calendar. oracle database releases
Here is your practical guide to the current Oracle Database release landscape—what is active, what is dying, and what you should deploy today. Since 2018, Oracle has maintained two distinct release families: 19c is the last release of the 12
21c was an innovation release that very few customers adopted. Its key features (native blockchain tables, JSON data type improvements, in-database JavaScript) were absorbed into 23c/23ai. That world is gone