It's a form of procrastination, especially frequent when you are tired, unsure of how to tackle what you're doing, or just don't like what you're supposed to be doing. The worst is when you run a compiler or something and it takes 5 seconds. You obviously can't just stare at empty space for that long so you go spend 5 minutes on the internet.

The slower your tools, the viciouser the cycle.

Opening the internet on encountering any sort of difficulty or setback in your task is a particularly vicious reflex. Sometimes I'm on my phone or checkinn slack or whatever before I even consciously realize whay I'm doing.

Pomodore helps bring a modicum of structure to that behavior by keeping me off the internet for 25min and then letting the flood gates loose for 5min. It fails in the face of slow tools of course.