Usage share, in web browser statistics, is the percentage of visitors to a group of web sites that use a particular browser. For example, when it is said that Internet Explorer has a 85% usage share, that means that 85% of visitors to a given set of sites used Internet Explorer. Typically, the user agent string is used to identify which browser a visitor is using.

Note that measuring browser usage in terms of the number of requests made by each user agent can be misleading. Not all requests are generated by a user, as a user agent can make requests at regular time intervals without user input. In this case, the usage of that user agent would then be overestimated. Some examples:

• A web browser that refreshes the web page at a regular time interval
• A feed reader that requests the RSS/Atom feed at a regular time interval

Note that the usage share does not suffer from this problem of overestimation, since it measures usage in terms of unique visitors to web sites rather than page hits.

References

• OneStat.com (November 22, 2004)
• WebSideStory (December 13, 2004) "WebSideStory Press Release." WebSideStory Press Room. Accessed on January 21, 2005.