The Korean alphabet is used for nearly all written communication on the Korean peninsula. There are a number of interesting things about it, many of which come about from its uniqueness: it isn't related to any other writing system on Earth. It's very popular in the Koreas, where literacy rates are high partly because it is easy to learn. Books, magazines, newspapers, TV and online media all use it except for occasional words that make more sense in English (e.g. "IMF*"). The only notable exceptions to this are in newspaper headlines and highbrow literature, where Chinese symbols are sometimes mixed with Hangul. However, this habit is sometimes considered a bit pretentious.

Here are some key facts:

1. It's no use for anything other than communicating with Koreans. That means you'll only get to communicate with about 50 million people if you learn it which, comparatively speaking, isn't very good value per unit effort. But on the plus side, Koreans are well worth communicating with on the whole, and they might even give you some kimchi to show their appreciation.
2. If you're quite clever it will take you about two hours to learn to read and write as well as a Korean eight-year-old. If you're more on a par with the author of this entry, it'll take you about a week. Either way, it's not very hard and several million Koreans will be very, very pleased with you.
3. You can really impress your European friends by reading it, as the text looks a tiny bit like Chinese at first glimpse. Like Chinese, a sentence is made up of a sequence of symbols of roughly square proportions. Unlike Chinese, each symbol is formed from about three letters from a simple alphabet that's easy to learn.
4. There are almost no exceptions to pronunciation in Korean. So it sounds like how it looks (assuming you've learnt the alphabet correctly, that is).
5. There are about twenty-four letters in the alphabet. Ten are vowels, which sounds like quite a few vowels. But the large number is mostly because different vowel-sounds have different letters (e.g. o and oh). Contrast with English, where the letter 'U' is the written the same in 'fundamentally' and 'confusing' even though the two sounds are completely different.
6. It's easy to type Korean because it's alphabet-based. The only difference as compared with Roman alphabets is that the computer has to form your key presses into groups of about three characters as you type.
7. It's written left-to-right then top-to-bottom, just like western European languages.
8. The alphabet was invented! A certain King Sejong decided that Koreans needed their own writing system to replace the complicated Chinese system. So during his reign, which began in 1418, a committee developed a scientific and straightforward alphabet from scratch. Literacy rates soared as the alphabet caught on, and although its usage waxed and waned over the following centuries, it is now used for nearly all written communication in both Koreas.
9. Since the writing system is alphabetic, the spoken languages in North and South Korea cannot diverge too far unless literacy rates drop to very low levels in North Korea. So we can thank King Sejong for ensuring that the North Koreans will still be able to share a joke with their Southern compatriots when their fifty-year isolation finally ends.