Looks like I'm most productive after lunch, from 2:30pm until 7:30pm. ( according to http://wakatime.com http://wakatime.com ) Side note, what is productivity

Looks like I'm most productive after lunch, from 2:30pm until 7:30pm. ( according to http://wakatime.com http://wakatime.com ) Side note, what is productivity and how to measure it? Is productivity a measure of your focus(less breaks/distractions/browsing FB), the number of lines you write, or the number of tasks you check off as done?