When discussing their web site traffic, different people often use different metrics. Three common metrics I see are Visits, Page Views, and Hits. If someone states that their application gets 1,000 X per day, depending on the metric used, the statement can have very different meaning.

When someone comes to a site and starts clicking around, that is considered a “visit”. No matter how many pages they click, files downloaded, etc… this is all part of the same visit. There are configuration changes that can be made that impact the specifics of the visit definition, but commonly a person is considered still on the same “visit” if they click a page at least every 15 minutes or so. If I go to a page on a site and spend 30 minutes reading the page before I click on another page – depending on the configuration and also the reporting tool – that can quite possibly be considered two visits.

During each visit the person will often click on a few different links, bringing up different pages on the site. Each one of these clicks to other pages would be consider a page view. Most statistics reporting tools with let you know how many pages on average each visitor clicks while visiting your site. Depending on the type of site and how the content is managed, there might be just a few page views – perhaps even just one per visit – or there might be many page views. Reporting tools will also often let you know how much time the average person spends between clicks – so you know how long they spend reading each page before moving on to another one.

Visits and Page Views are fairly straight forward. Where I see things getting a little cloudy is when people start discussing “hits”. I’ve seen some people say hits when referring to visits; other when referring to page views. Technically though, a “hit” would be every request to the web server. It is synonymous with the term “requests”, which I prefer to use.

A single page view isn’t just one request to a server. One request is made for the initial HTML, then another request is made for a javascript or css file (if used), another separate request is made for every image on the page, etc… So, a single page view can often have dozens of separate requests made to the server. Each one of those requests needs to be handled individually by the web server.

Using the Web Page Speed Report at http://www.websiteoptimization.com/services/analyze/ and looking at Microsoft.com this morning, I see reported that just a single load of the homepage generates 58 “hits” (HTTP requests) to the web server. Imagine the amount of work a server needs to do if there are hundreds of visitors at once, each clicking on a few pages, and each page is generating 50+ requests back to the web server. It helps one appreciate the power of Microsoft’s web services.

If you want to understand the popularity of a site and general traffic, visits and page views make sense to discuss. When you start talking about the load on the server and how much work it is doing, a discussion of requests made to the server – specifically the amount of requests in a short period of time, like requests per second – helps get a more accurate picture of the volume and load that the server needs to deal with.

Site owners rarely need to deal with or even consider the site traffic in terms of hits or requests per second – this is certainly more of an administrative metric and has the most value in evaluating architectural issues during load reviews or performance trending. It is good to at least understand the term and how it comes into play though. Hopefully this blog helps.

~Brad