によって / による

によって comes from よる, "to depend on", and marks the noun the rest of the sentence rests on. In English that comes out as "depending on", "because of", "by means of" or, in a passive, "by". It follows a noun directly; before another noun it becomes による.

"Depending on"

With a verb like ちがう違う or かわる変わる, によって says the result varies with the noun. This is the meaning you hear most in conversation.

によっては narrows it to some cases: "in some places", "for some people".

Cause and means

For a cause, によって belongs to news and written reports: accidents, disasters, delays. In conversation で or から is usual: たいふう台風でいえ家がこわれた壊れた. For a means, a verb goes in with こと: はなしあう話し合うことによって.

によって or に in the passive

An ordinary passive marks the doer with に. によって marks the maker with verbs of creating and discovering – かく書く, たてる建てる, はつめい発明する – and in formal writing.

• × 母によって叱られた → 母に叱られた

による and により

Before a noun the form is による: じしん地震によるひがい被害, "damage from the earthquake". により is the written way to end a clause, in announcements and reports.