What is Work?

I've been thinking a lot about the nature of work.  We can have very narrow definitions to what is work.There are both tangible and intangible parts to the work I do in the tech/internet industry. What constitutes work? Is it sitting a computer writing all day? Is it being out and meeting people? Is it when you're reading on an unrelated topic that suddenly sparks a good idea?

This is what work looks like right?

The way these guys were asking for money seems to mean this is work right?

Can work look like this--a big repository of minds?

Work these days is much more varied and increasingly lives in in our heads. So how do we know it's work? Is there always an output? Does it have to look a certain way?