Any sized business wanting to track and analyse customer behavior and interactions with their web pages.
Google Analytics offers tracking in several areas, including referral source tracking, time on site tracking, conversion tracking, site search tracking, keyword tracking, pageview tracking, and user interaction tracking. It allows users to segment their audience, for example, by location or age. It has a customizable dashboard and offers integrations with other apps and services like Google Optimize (which allows users to run split tests).
Google Pricing Overview
Google Analytics is a free service.