Know Your Traffic Language 
You should be aware of the different terms used to describe web site traffic, so as not to be confused about your web site visitors. Here are the main terms used:

Visit - these are all requests made by a specific user to the site during a set period of time. The visit is ended if a set period of time (say 30 minutes) goes by with no further accesses. Users are identified by cookies, username or hostnames/ip addresses

Hit - this is a request to the server for a file not a page.
Your page can be made up of different files, such as graphic files, audio files or css and javascript files, resulting in a number of hits for that page. Each of these requests is called a hit. 
Counting hits is not the same as tracking pageviews. It takes multiple hits to view a page. 

Therefore a site can have 100 images on it and if 1 visitor goes to the site it shows 100 hits. Hits are a very misleading form of reporting traffic. If you wanted a millon hits but only have a 1000 visitor a day all you would have to do is put 33 images or elements on your site an in a month that statistics will show 1,000,000 hits!

Pageview or Impression – this is the number of times a page is accessed as a whole. 

Unique View - A page view by a unique person within a 24 hour period. 

Referrer - A page that links to your site. By looking at your referrers will tell you who's linked to your site. This can be particularly valuable for seeing where your search engine traffic is coming from. 

User Agent - This refers to the software used to access your site. Sometimes known as a "browser" or "client", the term user agent can describe a PHP script, a browser like Internet Explorer, or a search engine spider like GoogleBot. If you can identify what software is being used to access your site, you'll be able to tell if users are abusing it, and when the search engines last crawled your pages. 

Ways to Track Your Visitors 

1. Counters - these are heavily used on web sites by newbies but appear unprofessional. It is very common to go to a page and see something like "You are visitor number 12345 to this page".
These numbers cannot be trusted as the page designer has the ability to seed the base number or to alter the counter such that it adds more than 1 each time. 

2. Trackers - tracking software details the path a visitor takes through your Website, so they do more than just count your traffic: they track it. Tracking software tells you more than just the number of visitor.s It can break visitor statistics down by date, time, browser, page viewed, referrer, and countless other values.