In marketing analytics, bounce or bounce-back is a term used to describe a single visit to a single page of a website. If a user opens your website and goes back or exits without hitting any other page on the website, he is said to have bounced-back. This means that it was only a single-page session and there was only one request to the Analytics Server.
The ratio of total no. of bounce back sessions to the total no. of sessions is called Bounce Rate. Here the user views a single page and triggers only a single request to the analytics engine.