Access to system allows you to limit access to your computer. When you include the computer or when you start the program — you it will be offered to enter the password. If the password correct you can further work with the computer, if not correct — you can not work with the computer. It protects from extraneous, wishing to do much harm to your computer. Also present statistics of access and you will know who and when included the computer. The program can be started at any time from the panel Quick Launch.