Unique Visitor
Used to describe one person visiting a site. That one person may generate multiple visits over a period of time, therefore log files normally show more visits than unique visitors. The shortened version "uniques" is sometimes used to refer to unique visitors.

URL
Uniform Resource Locator / Universal Resource Locator Each web page has it's own specific human-friendly URL, or web address. URLs are mapped to computer-friendly IP addresses by special computers called Domain Name Servers, or DNSs.