in virtual host this defines the collection of MIME type extension mappings defined for the virtual host. Virtual host MIME entries apply when you do not specify MIME entries at the Web module level.
MIME object defined the mime types.. do a google search or wikipeadia on mime types
here is a list of possible MIME Types :
www.webmaster-toolkit.com/mime-types.sht...==== ####====
.htaccess - this is a configuration file at directory level . This can be used for security restrictions on the directory.
Apache don't suggest using .htaccess files as it can slow down the operations. An alternative is to use tag in httpd.conf