Testing Software vs Playing with it

I was giving a Software Engineering lecture this afternoon and the conversation turned to testing. As it frequently does. So I asked everyone what they thought I meant by the word "test". One answer came back "it's what you do to see if it works". 

I don't think that's what I'd call testing. I was casting around for a phrase that fitted the occasion. Finally I came up with "Playing with the code". I wanted to get people thinking that actual testing is a lot more than just running with the program to see if it seems to do what we want. .

Proper testing is planned, repeatable and part of the creation process. And, if possible, automated. Don't make the mistake that the thing you do once it compiles is testing.  It isn't.