Question: explain how an operating system talks to hardware

title: Pre-installed software
text: It is usually licensed for use only on the computer on which it was pre-installed , and is not transferable to other computers . Its functionality is often time limited in an effort to get the user to purchase the `` full '' version . It often does not come with any media , should the user need to reinstall it . It sometimes modifies or replaces the default browser or system settings , in an effort to target specific advertisements to the user ; or may otherwise contain functionality the user might consider to be malware . It often consumes system resources , even if not actively being run by the user , adversely affecting system responsiveness and startup time . It is sometimes difficult or impossible for users to remove , such as via the standard uninstall utility provided by the system . Its purpose may be to install further unwanted programs without permission , or re-install them after the user successfully gets rid of them . It may consume bandwidth which a phone company can charge for ( especially on a phone device ) , yet not let the user know they are being cheated of some of their bandwidth . This may be a side effect of analytics or music downloads single unwanted apps are sending , but installing several dozen of these unwanted apps can drive the bandwidth costs up for a segment of users which would n't have happened without the unknown , uninstallable , unwanted apps .