I usually say: I help build an online advertising platform. Nope, I don't buy and sell ads. I work on the platform which we license out to people in the busi

I usually say: I help build an online advertising platform. Nope, I don't buy and sell ads. I work on the platform which we license out to people in the business of buying and selling ads. It handles more than 8,000,000,000 requests (200,000+/s peak) and several TB of data a day. From there discussion turns to their questions about advertising or scaling. Alternatively, I'll answer "Internet stuff, and some personal projects in my spare time". At any rate, a lot of people will always be misinformed about stuff they don't know much about but which they hear a lot about. Technology is definitely one of those things, as is the ".com garage millionaire" thing, as is this new work-from-home-x-hours-a-week. I wouldn't worry about it, but rather think of it as a chance to educate them a little bit.