What is the purpose of Overselling option in HC Panel

Question: What is overselling option mentioned at : Panel Configuration :: Configure Services :: General Settings at host level in HC panel?

Over Selling is the concept using in Shared Hosting Module where HC host allows a Reseller who can sell as many resources to the end users (Webadmin). And the Reseller will only require to buy further resources from the host if total allocated resources to a reseller  have been used by the end users.

For Example :  if a Reseller has 20 webadmins and this Reseller buys total 10 GB Disk Space from host. Now HC will allow reseller to create & sell many plans with different Disk Sizes i.e Plan A = 2 GB , Plan B = 7 GB , Plan C = 15 GB Size. As soon as Total Disk Usage under the Reseller reach to 10 GB then HC will generate a Disk Usage Warning email which will be sent to HC Host and Reseller. Now this Reseller will need to purchase more disk space from Host.