What are systemd targets and how does it compare with SysV init run levels

Systemd targets are represented by target units. Target units end with the .target file extension and their only purpose is to group together other systemd units through a chain of dependencies. For example, the graphical.target unit, which is used to start a graphical session, starts system services such as the GNOME Display Manager (gdm.service)

Comparison of SysV runlevels and systemd targets

Runlevel	Target Units	Description
`0`	`runlevel0.target`, `poweroff.target`	Shut down and power off the system.
`1`	`runlevel1.target`, `rescue.target`	Set up a rescue shell.
`2`	`runlevel2.target`, `multi-user.target`	Set up a non-graphical multi-user system.
`3`	`runlevel3.target`, `multi-user.target`	Set up a non-graphical multi-user system.
`4`	`runlevel4.target`, `multi-user.target`	Set up a non-graphical multi-user system.
`5`	`runlevel5.target`, `graphical.target`	Set up a graphical multi-user system.
`6`	`runlevel6.target`, `reboot.target`	Shut down and reboot the system.