If you wanted to collect the number of comments users posted to a webpage on your site, which of these would you set up?

If you wanted to collect the number of comments users posted to a web page on your site, custom metric should be set up.  Custom metrics are like default metrics in your Analytics account, except that  you have to  create them yourself. You can use them to collect and analyze data that Analytics doesn't automatically track.

These are very for instance for math pemdas parenthesis, exponents, multiplication, division, addition, subtraction without that i would never be able to remember what to do first with it i can remember.