The plugin used for Protection Zones is called Guardian.

Command: /G

/G Tool – Get a Guardian Tool, used to display zone info. Hit the ground with it. This is how you find the name of a zone.

/G Block – Get the default size of Guardian Block (30,256,30)
/G Block [x] [y] [z] – Get the specified size

Placing a G Block will create a protection around the block for you.
The zone created by the block cannot overlap any other zone.
Higher ranks gain access to larger sizes.

Admins will happily create a much larger zone for you whenever you ask.

Where commands use [zone] this is the zone name.
If you stand in your zone and use the command, you do not need to specify the zone name.

/G [zone] allow [player] – Allow a player to build in your zone
/G [zone] disallow [player] – Disallow a player from your zone
/G [zone] toggle [flag] – Toggle a flag on/off for your zone
/G [zone] toggle list – This will show the available flags to set

You can toggle protection to allow everyone to build, while still claiming ownership of the zone.
You can enable PvP for your zone (it is disabled by default).
You can allow/disallow mobs spawning.
And much more…