Computer systems today have large amounts of storage space, and a number of applications running at any given point of time. It is quite normal for a user to forget the kind of applications that are installed on the machine, and more importantly, what impact these applications have on computer security.
What Belarc Advisor does is that it scans the computer in question, and creates a detailed profile of all the relevant information it finds. This kind of information could include details of installed hardware and software, or missing Microsoft security hotfixes, among many other details.
The application then generates a detailed report of the same, and publishes it to an HTML file, which is then displayed in a browser.