Today's topic of the #90DaysOfDevOps challenge is package management and service control using systemctl.
The task solutions include Docker installation and Jenkins installation, along with commands to manage services using systemctl.
Package management commands include APT for Ubuntu/Debian and YUM for CentOS/RHEL.
Key takeaways include simplifying software installation with package managers, using systemctl to manage system services, troubleshooting with service logs, and the importance of boot-time service management.