Cacher is the code snippet organizer for pro developers

onclick="ga('send', 'event', 'category', 'action', 'opt_label', 'opt_value');"

There are a few variables that will change with each different event you track:

Category – grouping events into desired tracking groups
Action – the action the user takes
Label – to differentiate this event among the others (optional)
Value – perceived dollar value of event (optional)