Spikes on a graph are a symptom of something that happened.
Did you get a bump in site visitors because of a tweet someone sent out?
Or was it a boost in sales because of a special promotion?
Maybe it could have even been a drop in potential customers contacting you because of a faulty link on your site.
It’s easy to see the spike on the graph. It’s another to know why it happened. But most importantly, these bits of information do us no good unless we know what to do next.