Logical Volumes are similar to extended partitions in the fact that they can contain more then one filesystem. Some of the Advantages of lvm’s is
* They can span more then one Disk
* Can be resized on the fly
* Partitions within can be resized on the fly
The above advatanges make lvm’s easy to backup and encrypt, it is also easy to add new partition or disks to an existing lvm which makes them ideal for server as this should save on downtime. Also ideal for those who are new to linux or unsure of how much space to give to linux partitions like / and /home. Most linux distrobution installers support installing into an lvm.
Below is a picture of how lvm’s work.