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.
To add the worker process account to the IIS_IUSRS group. Click Start and then click Server Manager. In the Server Manager screen, expand Configuration, expand Local Users and Groups, and then click Groups. Right-click the IIS_IUSRS group, and then click Add to Group.