What is a tester?

It sounds like a silly question, but lately I've been in a lot of conversations where the topic of what a tester is, or what a tester does has come up.  The answer, of course, varies.

I know some companies have different roles for "testers" (people who do various manual testing tasks), and "automators" (people who write test automation).  Many organizations have a Quality Assurance (QA) staff who may do testing, or may be true QA (the QA title has become so bastardized and convoluted that it's hard to tell what they do - I'll save the rest of that rant for another post).

At Microsoft, most of our testers write automation code.  Others don't write automation at all (most of these are not stereotypical button pushing testers, but own maintaining extensive infrastructure or reporting systems in addition to doing ad hoc or exploratory testing).  Some testers do "real" QA work too - there is no such thing as a QA title at MS, but senior testers often pick up a lot of the traditional roles of QA (there's a rant I could put here about teams calling their testers QA, but as I said above, that will be in a later post).

So what do testers do? 

The answer varies within Microsoft, and varies much more when you consider the entire testing community. 

I've been working at MS for nearly 11 years, and I still have a hard time describing what I do to my mom. 

If your mom asks what testers do, what do you say?