Most dictionaries list Korean verbs under a form, known here as the Dictionary Form, which ends in 다. (Let us call the part before 다 the stem.)
Korean has several styles of speech, for example:
Polite Form. Verbs end in 요.
Intimate Form. The form is the same as for Polite, but knock off the 요. Used in the family or to people you know very well and are not older than you.
Formal Style. Verbs end in 습니다 (ㅂ니다 if the stem ends in a vowel). Used in formal situations such as with people you don’t know, during interviews, on the news, in the army and to teachers or senior people.
These are frequently used forms; we will add others e.g. the Plain Form at a later stage.
You can make the Intimate Form by removing 다 and adding 어 (아 if the last vowel in the stem is ㅗ or ㅜ) if the stem doesn’t already end in 어 (or 아). Once you’ve got the Intimate Form, you can form the Polite Form just by adding 요.
You can make the Formal Style by removing 다 and adding 습니다 (ㅂ니다 if the stem ends in a vowel).
Example: in the dictionary you will find 먹다 “eat”. You can make 먹어 “eat (Intimate Form)”, 먹어요 “eat (Polite Form)” and 먹습니다 “eat (Formal Style)”.
In Korean verbs are so like adjectives, that it makes more sense to speak of Processive verbs and Descriptive verbs. We will stress the small number of differences as they come up.
It is recommended that you say these forms out loud, so that they trip off your tongue naturally: