Learn English – Looking for the label that books get when they out of use (at the library)

At your request, I will say that Ssav's answer is the one I would select. This is because the word hearer, though it is perfectly correct, sounds awkward to me. Stoney is not wrong at all, this is simply my own preference.

John spoke to Mary. He spoke and she listened.

The speaker noted that the flowers were beautiful and his listener thought that he was right.

None of these are examples I'd use in writing, however. It just sounds strange.

When John/he spoke, Mary/she listened intently.

If Mary was another man, then he and he could not be comfortably used.

While he spoke, Mark listened.

I am not at all sure I've added anything that helps.

"a) You have to always know your second person (the person you are talking to) and speak accordingly.

b You have to always know your spoken to (the person you are talking to) and speak accordingly. [It sounds a bit odd to me.]"

should be, imo:

You have to know your listener (but audience is better) and speak accordingly.

You have to know your audience and speak their language.

You have to know your audience and speak to their level of knowledge/expertise.

Audience works better and can absolutely be used even if the audience IS one person.

In contemporary English, one sees the expression: the system is rigged against the poor; a rigged system.

This was a term used by Bernie Sanders in the US election: rigged economy.

But "a rigged system" can apply to many things, including voting.

It's such an interesting term as it dates back to the rigging of ship's sails. Elections are also said to be rigged.

All dictionaries give the two meanings: re ships and how something can be set up dishonestly to benefit the few. When you look at a tall ship, fully rigged, you can see how the term came to mean what it does: full-rigged sailing vessel

Here's the Merriam Webster's definition: rig

rigged economy

On sailing ships (tall ships), it is the captain who orders sailors to set the rigging (all the lines to sails and which sails are furled or unfurled) to his (or her!) own liking. As such, they control the ship and how it is sails through the sea(s).

One can say that captains have total say over the rigging. And in the literal sense, it does not mean what it has come to mean today in politics, economics, etc. where such a negative connotation remains of what is actually a beautiful thing. [There are many tall ship events around the world and its an amazing sight to see these old vessels sailing into a harbor. In fact, you can go on some of them and they will teach you how to rig the sails!]