Bounce Rate refers to the rate at which a visitor "bounces" from your website. A bounce is when a visitor lands on your website, and leaves before visiting another page. Bounce rate is a statistic rumored to be used by Google in new behavioral search reporting method.

It's a best practice to strive for a website with a low bounce rate.

Time spent on site is a phrase that refers to the amount of time a visitor spends on a website before leaving. The idea is to create a website that encourages visitors to spend as long as possible on the site. It is rumored that this is a statistic that Google is currently using in their calculation of search engine results pages.

It is a best practice to create websites that encourage visitor participation and loyalty.