Talk casually with friends
With friends and family ます and です fall away. The verb stands in its plain form, です becomes だ or nothing: あした いく, ねこだ.
JLPTN5
いきます → いく · です → だiku · da
Same sentence, shorter ending. The verb stands in its plain form — the form you sort verbs by: あした いきます becomes あした いく; たべます becomes たべる; します becomes する. Negative is the ない-form: いかない, たべない. Past is the た-form: いった, たべた.
です becomes だ, or drops entirely: ねこです becomes ねこだ or just ねこ. い-adjectives stand as they are: たかいです becomes たかい. Questions lose か and are heard in the tone: いく? — なに たべる? The form suits friends, siblings and people your age you know. With the teacher, in a shop and with adults you do not know, it is ます and です.