Unicode Text in JavaScript: How Fancy Text Generators Actually Work

Have you ever wondered how text like this works?

𝐇𝐞𝐥𝐥𝐨 𝐖𝐨𝐫𝐥𝐝

or:

𝓗𝓮𝓵𝓵𝓸 𝓦𝓸𝓻𝓵𝓭

It may look like someone simply changed the font, but in many cases something more interesting is happening: Unicode characters are being used to create the visual effect.