What is Bounce Rate in Google Analytics?

Bounce rate in Google Analytics is a marketing term used to measure the portion of visitors who enter a website and then leave from the same webpage they have entered, rather than continuing to browse the website and view other webpages.

How does Bounce Rate in Google Analytics Calculated?
Bounce rate in Google Analytics is calculated as a session that triggers only a single request to the Analytics server, such as when a user opens a single page on your site and then exits without triggering any other requests to the Analytics server during that session.