The GNU Linux distribution Ubuntu 18.10 codenamed Cosmic Cuttlefish It will reach its end of life in a few days, specifically on July 18 of this year 2019. Canonical has recently announced it and that means that everyone who has this operating system installed will have to think about a new version if they want to continue receiving security updates and patches. Otherwise they will be in a somewhat complicated situation without this support provided by the British company.
That something logical, the previous versions are always being stopped to attend to new ones. On October 18, 2018 Ubuntu 18.10 was released and since then we have been able to enjoy it. Now go to new life. You can update to the new Ubuntu 19 easily by command or from the graphical Ubuntu update system. Do it however you want, but sticking with that version is not recommended for obvious security reasons.
Ubuntu 18.10 it was not an LTS version (Yes it was Ubuntu 18.04, in that case you can rest assured) as you know, it only had a support cycle of 9 months, so it is no surprise. Personally, I always avoid the short cycle versions and I always install the LTS to spend more time with them without these types of problems. But there are those who prefer to always have the latest features and news. Total, if they can update whenever they want ...
Ubuntu 18.10 brought GNOME 3.30 (no longer the famous Unity Shell that Canonical popularized) as the base desktop environment, and the Linux 4.18 kernel, new features, a new look, better integration with mobile devices, support for Thunderbolt, and much more. But what seemed a novelty a few months ago has been overtaken by Ubuntu 19. If you update to Ubuntu 19.04 Disco Dingo now, you will have support until January 2020, it is not a long support, but enough not to be unprotected.