hanamaru
Tell a verb's type
Every verb is ichidan (る-verb), godan (う-verb), or irregular — the class decides how it conjugates.
Example Sentences
I'm going to eat breakfast!
Want to drink water?
Verb Endings Matrix
Japanese verbs come in two kinds, plus two irregulars. RU-verbs end in いる or える: たべる, みる, おきる. When an ending is added, る is dropped: たべる → たべます, たべて, たべない. U-verbs end in some other u sound: のむ, かく, いく, はなす, かえる. There the final sound is changed — to the i row before ます (のむ → のみます, かく → かきます), to a sound that depends on the verb before て (のんで, かいて, はなして, かえって), to the a row before ない (のまない, かかない). する and くる are the two irregulars.
How to tell the kind: if the verb ends in いる or える it is usually RU, otherwise U. A few verbs end in える or いる but are U-verbs anyway — かえる (go home), はしる (run), しる (know), きる (cut) — so the kind belongs to the word: learn it when you learn the verb.
Everything you do with a verb later — polite form, て-form, negative, past — starts with this sorting. That is why it comes first.