となる - Grammatical explanation please


can someone please explain となる ? I read it everywhere but still don't know
what it exactly means.

Here's just an example sentence:

> この世界が心つなぐ鍵となる




I'm not fluent with Japanese and can't read Kanji, but I think となる means "to
become" or "to change" into a final state.

This site might help give you a better explanation - [It focuses on the
differences of になる and となる, but also gives it's meaning.
](http://www.sljfaq.org/afaq/to-naru-ni-naru.html)

この世界が心つなぐ鍵となる - I'm sorry I can't translate this but in Romaji it would look
like this > kono sekai kokoro tsunagu kagi tonaru. Translated literally it
might look like this > (kono)This (sekai)world (kokoro)heart (tsunagu)to tie,
fasten or connect (kagi)key (tonaru)to change into final state.

So possibly > This world's heart is tied (or bound) to change?

Sorry can't read Japanese _yet_ so hopefully this helps.

