Look at this public service advertisement. A poster that reads, "Vaccinated? Get a booster!"

What is the purpose of this PSA?

to convince people to become astronauts
to convince people to get their vaccinations
to convince people to boost their knowledge of bees
to convince people to learn about space travel

To convince people to get their vaccinations

The answer is to offer a warm place to sleep and have conversations after a meal.

In the words of Benjamin Franklin in an essay he wrote about Native Americans...

There is in every village a vacant dwelling, called the stranger’s house. Here they are placed while the old men go round from hut to hut, acquainting the inhabitants that strangers are arrived, who are probably hungry and weary; and every one sends them what he can spare of victuals, and skins to repose on. When the strangers are refreshed, pipes and tobacco are brought; and then, but not before, conversation begins, with inquiries who they are, whither bound, what news, etc.; and it usually ends with offers of service, if the strangers have occasion of guides, or any necessaries for continuing their journey; and nothing is exacted for the entertainment.