What is the difference between 語{かた}る and 話{はな}す?

Question

What is the difference between 語{かた}る and 話{はな}す?

I know that I can say #1, but it's correct to say #2? If it's ok, sentence 1 and 2 have the same meaning?

1.私{わたし}は日本語{にほんご}を話{はな}す。

2.私{わたし}は日本語{にほんご}を語{かた}る。

Answer 1

私は日本語を話す。 I speak Japanese.

私は日本語を語る。 I talk about Japanese.

Since 語る has no special meaning associated with languages, it only means that you are talking what you know or how you feel about Japanese. It's quite popular in Japan to give the title ～を語る to books that celebrities reveal something or specialists express their thoughts.

Though I translated 日本語を話す into "speak Japanese", the verb doesn't have "be able to speak" sense, so every time you have to explicitly use potential form when you question about ability.

日本語が話せますか？ Do you speak Japanese?

compared to:

日本語を話しますか？ Are you going to speak Japanese?

A Japanese thesaurus has a neat summary including the difference of 話す and 語る:

	...loudly	...a perceptive comment	... English	... one's past	...oh! (a yell of surprise)
言う	○	○	×	×	○
しゃべる	○	△	○	△	×
語る	○	△	×	○	×
話す	○	△	○	○	×
述べる	○	○	×	×	×