What does "It's a brave new world" mean?

The phrase “brave new world” originated in a line from Shakespeare’s play The Tempest: “O brave new world, / That has such people in’t!” Aldous Huxley borrowed it for the title to his novel of the same name. You will understand the usage of the phrase better after reading these works. They are both classic works that are worth your time. You can also probably find film adaptations of them.

@Zissou I mean in everyday use. If you used it, let,s say.

“brave new world n [fr. the dystopian novel “Brave New World” (1932) by Aldous Huxley] (1933) : a future world, situation, or development; also: a recent development or recently changed situation” – from Merriam-Webster’s Collegiate Dictionary, 11th. ed.

I’m thinking we will soon be using it for the Singularity in relation to Artificial Intelligence.

Consistent with the above, I in a general sense think of it as major changes that alter the world as we know it. It can be a technological change, or a major change in relationships between countries, or even a major medical advancement.

@Zissou is absolutely correct. You can have a superficial comprehension of (others’ take on) the meaning of the phrase and believe that you have acquired thereby some kind of pseudo-understanding… or you can read the works that the phrase comes from and have an actual, real understanding. You can also find out that it’s others who misunderstand the labels and metaphors and allusions that they make.

I kicked myself recently because I did exactly this. I heard someone describe a brilliant black man whom I have admired for many years an “Uncle Tom”. Because I have a vague understanding of a lot of English & American literature just from exposure – without having read some of the works where the phrases come from – I knew that this was a reference to the title character in Harriet Beecher Stow’s novel of slavery in the United States, Uncle Tom’s Cabin. But I had no idea what the phrase actually meant, or the exact characterization that the speaker implied. Well, I’ve now read the book. And it’s plain to me that the speaker who made that assertion without a real understanding of the character was completely mistaken. And Aldous Huxley is on my reading list, too.

To admit ignorance is the beginning of wisdom. To pretend knowledge is to cement ignorance in place.

Brave New World:
It has diverse meanings from my perspective. e.g, It could indicate the world, that has been profoundly sexualised or it could mean, a world that has been reborn, has become new, has been washed from its sins and dirt or it could mean how technology has impacted and influenced us.
I would say the second guess is, somehow, true because if we take a look at the full quote “How beauteous mankind is! O brave new world” it points out the positive side of humanity, and is being optimistic.