Google Analytics is a free tool that provides more data then the average website owner can digest. It can be connected to Google Search Console to provide even more insights.
Standard reports include key data such as visitors, page views, landing pages, keywords, bounce rates, referrals, geography, e-commerce sales, goal conversions and more.
You can augment your usage of Google Analytics by importing custom templates from their solutions gallery or from a number of third party sources. You can also take your data on the go by utilizing apps for mobile devices.
Every website and blog should be using this free tool and utilizing the data within their marketing strategy and planning efforts.