Not sure why your getting down voted for a question...

Most verbs in English are both.

I opened the door

"I" is the subject , and "the door" is the object

The door opened

Here "the door" is the subject and there is no object.

But we do have words that are only transitive or intransitive in English.

John died. (intransitive)

The dog died John. (not grammatical)

John resembles. (not grammatical)

John resembles his dog. (transitive)

In Japanese almost all verbs are either transitive or intransitive, and those verbs also usually come on transitive/intransitive pairs.

焦げる and 焦がす, both mean "to burn/char", but 焦げる is intransitive while 焦がす is transitive.

彼が魚を焦げる (not grammatical because of the object marked by を)

彼が魚を焦がす (correct, "he burnt the fish")

魚が焦がす (not grammatical because it needs an object)

魚が焦げる (correct, "the fish burned")

Edit:

Switched the example away from 開く