In addition to tracking users at a session level (how many times someone accessed your site), you can also gain valuable insight by tracking “unique” users or “unique” visitors.
An individually identified web browser requesting pages from a website (“Log Analysis”) or viewing pages (“Page Tagging”) within a given time period (i.e. day, week or month). Analytics tools count “Unique Visitors” only once within the timescale (often 30 days, though the timescale is frequently configurable; please consult your analytics vendor for more details). A “Visitor” can make multiple “Visits” during that period from the same computer/browser without increasing the “Unique Visitor” count (note, however, those subsequent “Visits” do increase the “Repeat Visitor” metric). Identification is made to the visitor’s computer and web browser, not the person, most often using cookie and/or a combination of the visitor’s IP Address and web browser. Thus the same person using two different computers or with two different browsers will count as two “Unique Visitors”.