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 can do more than just brighten your day .

Correspondent Rhitu Chatterjee reported on studies showing that simply chatting with strangers has a lasting impact: It can make the participants happy. Even smiling and waving hello to a vendor you see regularly can boost your spirits, says psychologist Gillian Sandstrom , who delved into the benefits of social ties after her own uplifting exchanges with a hot dog seller during a time when she was feeling really isolated.

The article struck a chord with readers, who shared their own stories of random encounters. And it keeps on inspiring people. A few weeks ago, we heard from Kristin Jenkins, an infection preventionist and a global health professor at Cornerstone University in Grand Rapids, Mich.…