Inventory management can be used to track the stock of items. Items can be identified by unique serial numbers. Using that unique numbers inventory system can keep track of item and trace its current location in the organization.
e.g. you have purchased 150 hard disks, so using inventory system you can track how many hard disks are installed, where they are installed, how many hard disks are remaining etc.
Inventory management includes functionalities like inventory control, master units, stock utilization reporting etc.
There may be an integration of the inventory module with the purchase module of ERP.