It’s a real minefield for terms about websites out there. I heard on the news about some site receiving 16 million hits in a week or so. But that’s not necessarily 16 million individual visits, or 16 million unique visitors. A unique visitor for example might visit several times a day or week, notching up many hits. But the perception by the general public might be that 16 millions hits means 16 million visitors.

Hits

Hits aren’t a real measure of traffic, but they do generate the biggest number for webmasters to spout off. This is basically the amount of requests made for files on a web server. One single view of a page (pageview) may generate tens of hits.

Files

The second most worthless metric to have (after hits). A file is when a remote server requests a file and something is sent back. This does not count 404s or those pages that are in the browser’s cache.

Pageviews

Pageviews can be counted alongside visits but pageviews are artificial. Take this example, I visit your site, but I go from the homepage to another page, then back. That’s one visit, but three pageviews.

Impressions

Say I have two banners or graphic ads on a page. With 1000 pageviews, I would have two thousand impressions. This is a marketing term only and should not be used to accurately guage (or quote) traffic levels.

Visits / Unique Visitors

A visit is where a remote server requests a page from your server. Note this does not mean one server requesting a graphic file from your server, i.e., loading up graphics of yours.

This is essentially the most important metric to be concerned about. A visit can mean one person browsing your site for a few minutes or several hours (generating many pageviews and many more hits).