Web analytics involves collecting and analyzing digital data about user behavior on websites and mobile apps. It is important for measuring the effectiveness of marketing campaigns and ensuring websites meet their objectives, such as increasing sales for ecommerce sites. Google Analytics is a popular web analytics tool that tracks user data through a JavaScript code added to websites. It provides visualization tools and insights about key metrics like users, sessions, pageviews, bounce rate, and exit rate, broken down by dimensions such as channels, devices, and locations.