greetings.](https://npr.brightspotcdn.com/dims3/default/strip/false/crop/3200x1800+0+0/resize/1100/quality/50/format/jpeg/?url=http%3A%2F%2Fnpr-brightspot.s3.amazonaws.com%2Fa2%2Fce%2F1af6d788491e80ddbeeeb6a09fb4%2Flaura-gao-illo.jpg)
Laura Gao for NPR
Hello, stranger!
That's a good thing to say, as we reported in a story we published three years ago: [**Why a stranger's hello