When you install OS X Lion, the system will create a hidden partition called "Recovery HD." In addition to providing recovery and diagnostics tools similar to those on the older OS X installation DVDs, it is also used for enabling enhanced features in Lion such as Apple's FileVault 2 disk encryption and the "Find My Mac" location service as part of iCloud.

While this partition should be present on most systems running Lion, in some situations it may be missing. If you've installed Lion on a drive with too many partitions or an unsupported RAID array, then while the Lion installer will allow you to continue the OS installation, it will just omit setting up the Recovery HD partition.

In addition to unsupported drive configurations, you can inadvertently remove the Recovery HD partition if you format your drive and restore from a cloned backup. While block-level cloning of a drive will preserve its partitions and the data on multiple volumes, this cannot be done on the boot drive so an alternative that is more commonly used is file-level cloning that copies all the files from one volume to another. Unfortunately doing this will only copy the files from your OS X installation and not from other partitions like Recovery HD, so if you have cloned your system to an external drive followed by repartitioning and formatting your internal drive and restoring, then you likely will have removed the recovery HD partition.
Disk Utility showing hidden partition

With all partitions shown in Disk Utility, you can see whether or not the hidden Recovery HD partition is present on a drive.

To see if your system contains a Recovery HD partition, you can restart with the Command-R keys held down. If your system boots to the recovery tools, then the partition is present. Optionally you can enable the debug menu in Disk Utility, followed by selecting "Show every partition" in this menu to see if the Recovery HD partition gets listed in the tool (it should be grayed out).

Check more info of Macintosh Partition Recovery Tutorial at http://www.recover-data-mac.com/partition-data-recovery-mac-software.html