Java is a programming language and computing platform first released by Sun Microsystems in 1995. There are lots of applications and websites that will not work unless you have Java installed, and more are created every day.
IIS is able to impersonate the IUSR_<computername> account because the user name and password for this account are known by IIS. Before returning a page to the client, IIS checks NTFS file and directory permissions to see if the IUSR_<computername> account is allowed access to the file.
The IUS is licensed for contraception for 5 years but if it is inserted over the age of 45 years it could remain in place for 7 years after discussion with your doctor or nurse. It is only licensed for 4 years if used for HRT but is known to be effective for this purpose for 5 years.