Your Web page tracks activity using a number of passive measures, including impressions and visitors. The two are distinct in what they measure, with the former incrementing only when a page is accessed, and the latter counting only when a unique address comes to your website.
Pages Versus Websites
To understand the distinction between impressions and visitors, you need to understand the basic components of a website. A website is typically comprised of a number of different pages. Clicking on a link within the website opens individual files. These files are stored on a Web server, the directory for which defines the overall website. A single website, for example, could have a separate News page and an About Us page within the same structure.