It happens every day.
You're going to the dentist/supermarket/PTA meeting and you run into someone you haven't seen in years. What happens next? Recognition, check-ins on one another's families and then, the inevitable question: "So, where are you working now?"
And just like that, you're on stage and have to demonstrate that (a) you know what you do for a living; (b) you can describe it to an outsider; and most importantly (c) you can sell it to this person who may be a prospective client.