Why Should I Use Different User Accounts?
Current Windows operating systems support multiple users. There are at least three types of users: guests, standard and administrative users. When working, you should use a standard user. This minimises the risk of accidentally installing unwanted software or modifing the system.
If you need to install software or make modifications to your system, you can switch to an adminsitrative user. On newer Windows systems, this is done automatically by a process called User Account Control (UAC) which displays a dialog box and asks if you want to allow that modifications are made.