If you need to check what CPU is installed on your computer or how many memory do you have, you can open a System information in Windows and find required information there. But it is missing information about a number of occupied and free memory slots, that is required if you plan a memory update. Information about other hardware components is available in other Windows dialogs or through drivers, but in total over 90% of all inventory information isn't available. Nevertheless, it's available for a system and you can use various system utilities to extract detailed specification for installed memory modules, for example. Other utilities can be used to report information about a graphic card, so you have to use different tools to extract inventory information about a computer. Just imagine how many time you need to extract this information about all computers from a local network.

If you need to collect inventory information from multiple computers you can visit them one-by-one, install required system utilities, export collected data and import it into a centralized inventory database in order to create inventory reports. But there is a less daunting way and you can use specialized network inventory software that is designed to collect inventory information from multiple computers into a centralized repository. Network inventory tools allow collecting information remotely from computers connected to a local network, so you can get inventory data from selected computers in automatic mode with no time-consuming manual actions.

Network inventory software can be classified by approach used to extract inventory information. First category of applications require installation of client modules on network computers. Software and hardware audit information is extracted locally by this module and then inventory tool communicates with this module to extract collected data into a centralized database. It is possible to extract any kind of inventory information available for Windows using this approach, but it requires installation of client modules on all network computers that can take a significant amount of time. Also it's hard to maintain client modules in order to upgrade their versions, install them on all new computers, etc.

Another category of inventory software is called clientless because such tools can collect inventory information from network computers without installing client modules on them. Usually such tools use Windows Management Instrumentation (WMI) technology from Microsoft to collect inventory data over a network. For security reasons on latest operation systems starting from Vista WMI is disabled by default, so if you like to use a network inventory tool based on WMI you need to configure your network environment. You need to use an administrative account to connect to network computers, turn off a set of standard services and configure firewalls on computers to enable communication using WMI.

There are some inventory tools that also use a clientless approach, but don't use WMI to extract inventory data due to WMI security holes. Usually such tools can extract hardware and software inventory information remotely by connecting to registry on network computers. All inventory information is stored in the Windows registry, so it's possible to extract it directly over a network. This approach requires minimal configuration - you need to use administrative credentials to access remote computers and make sure that remote registry service is enabled, so it's the fastest and easiest way to collect inventory information.