If you are asking when the first monologues (speeches or orations delivered by one speaker only) were given, we have evidence that even thousands of years ago, in Bible times, great leaders (such as the Prophets) gave these kinds of talks. But if you are asking when monologues became popular on the stage, that too can be found thousands of years ago, in Ancient Greece, where authors and playwrights made use of them: there is evidence of monologues by Sophocles and Euripedes, for example. And monologue was also frequently used centuries later by Shakespeare.
A synonym for monolog is soliloquy.
He and her.
yes
Good monolog sites are the ones you can see on television. The major networks have late night television shows. Each of these talk shows starts off with the hosts doing a monolog.
soliloquy.
omanilikeweinerz
...a monologue.
dialogue
solilquy....
mono-logue
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Less than two people.