自動詞 is an intransitive verb and 他動詞 is a transitive verb, but they are not exactly the same as English intransitive verbs and transitives verb . 自動詞 does not require an object. But 他動詞 requires an object which is preceded by a particle を, and it expresses an action upon the object. On the other hand, when we use 自動詞, which is usually preceded by a particle が, there is no concern over who or what takes the action. That is, the difference between the usage of the two types of verbs depends on whether there is someone "doing an action" (他動詞, which literally means "someone else verb") or not (自動詞, which literally means "self verb") 開ける／開く 私はドアを開ける　(I open the door.) --> 他動詞 ドアが開く　(The door opens) --> 自動詞 消す／消える 私は電気を消す　(I turn off the light.)　--> 他動詞 電気が消える　(The light is turned off.) --> 自動詞

I think this is applied to English. (1)見つかった→I was found by someone.(私は誰かに見つかった） (2)見つけた→I found someone. So if you use 見つかる,"I" must be an object.If you use 見つける,"I" must be a sublect. P.S. I used the past tense for convenience.

Okay, I think I have started to understand the difference in meaning and usage between tadoushi and jidoushi. It is similar to English (in)transitive verbs, of course, but I don't think it's productive in really succeeding in the language to think that way all the time (by comparing everything to another language you know more fluently, especially if it's your L1). And I think I'm noticing some patterns: words that end in -eru or -ero or -aru are usually tadoushi. Are the jidoushi and tadoushi versions of a word considered to be different words or different forms of the same word? Is there a pattern to which verbs are ta and which ones are ji (I mean in the shape of the word, not their function or collocations in a sentence)? And I'm pretty sure this is different than Go-Dan and Ichi-Dan verbs. Is that correct? I never really got the hang of godan and ichidan. Maybe I should read some new grammar books now that my level is higher. Thanks for obliging my endless questions, 皆さん、ありがとうございます！