Robert Frost really started this whole thing rolling. He was, I believe, the first poet who started going to colleges. Before that, poets didn't give public readings very often, certainly not - there was no circuit of schools.
I do a lot of readings.
Even famous poets such as Marianne Moore and William Carlos Williams were rarely asked to read their poems.
Every single day, authors read at bookstores and libraries - and coffeeshops and bars - all over the country. And these readings are amazing: you get to hear the book in the author's own voice, ask questions, and meet the writer. For free.
What is a literary festival? Imagine a sort of cross between school and church. There are no actual festivities; what there are is a lot of public readings.
The world is crawling with authors touring now. They're like performance artists.
Audience participation can often inject a dose of adrenalin into your average dial-tone literary reading, especially if a handful of audience-members are mentally unhinged, and let's face it - you can always depend on at least one crackpot at these things.
When I began, poetry was very academic. You published little pamphlets from fancy presses. It was rather... chaste. There wasn't much public reading. Then there was poetry and jazz, which I don't think worked, though I love jazz.
The listeners who buy books after a reading multiply that reading; the author who realizes that he or she may be writing on a blank page but is at least not speaking to a blank wall may be encouraged by the experience, and write more.