Google Analytics Goal Setup
Setting up goals in Google Analytics is the best and easiest way to measure the success or conversion rate of your website. Only when you track and measure your data can you analyze and optimize your website further.
Google says:
Use Goals to know when visitors complete individual actions.
Goals are a versatile way to measure how well your site or app fulfills your objectives. You can set up individual Goals to track discrete actions, like transactions with a minimum purchase amount or the amount of time spent on a screen.
You must define and set up Goals in your Google Analytics account before data appears in your Goal reports and other reports that provide data on Goals and Goal Conversions.