• Basic forms
• 食べる — to eat / base form
• 食べます — eat (polite) / masu form
• 食べた — ate / ta form
• 食べて — eat and … / te-form
• 食べない — do not eat / negative
• 食べれば — if (someone) eats / conditional
• Common expressions
• ご飯を食べる — eat a meal
• お菓子を食べ過ぎた — I ate too many sweets
• もう食べた？ — Have you eaten already?
• まだ食べてない — Not yet (I haven't eaten)
• More
• 食べたい — want to eat / 〜たい form
• 食べられる — can eat; be eaten / potential / passive
• 食べよう — let’s eat / 〜よう form
• 食べている — is eating / progressive

食べる（たべる） is an ichidan (る-verb). Drop る and add endings like ます, た, て, ない. It’s the standard, neutral verb for “to eat” in everyday Japanese.

• Basic forms
• 食う — to eat / base form
• 食います — eat (polite, but rough-rooted) / masu form
• 食った — ate / ta form
• 食って — eat and … / te-form
• 食わない — do not eat / negative
• 食えば — if (someone) eats / conditional
• 食え — eat! / imperative
• Common expressions
• 飯を食う — eat (a meal) (rough)
• 早く食え — Eat up. (rough)
• More
• 食える — can eat; (also) can make a living / potential
• 食えない — can’t eat; can’t make a living / negative potential
• 食おう — let’s eat / 〜よう form
• 食っている — is eating / progressive

食う（くう） is a godan verb ending in う. It’s a rough/casual counterpart to 食べる, used more in blunt speech (often masculine), set phrases, or strong tone. The stem alternates as 食わ → 食い → 食え.