Visitors are one factor that should be known from the website owner. By knowing the visitors, website owners can improve their performance.
Counter and web analytics are the most effective ways to identify website visitors. some kind of counter which is currently widely used as to detect the browser, ip, keyword, geographic location, internet providers, etc.

Many large companies are jumping into the field of counter and websites such as google analytics, alexa, etc..

Some providers counter and web analytics include:

1. Google Analytics

Google wants you to attract more of the traffic you are looking for, and help you turn more visitors into customers.

Use Google Analytics to learn which online marketing initiatives are cost effective and see how visitors actually interact with your site. Make informed site design improvements, drive targeted traffic, and increase your conversions and profits.

2. HiStats

3. GoingUp 

4. StatCounter

5. SiteMeter

6. FlagCounter