Grammar · い-adjectives
い-adjectives, the basic form
[い-adjective] です
い-adjectives end in い and carry their own tense, so they do not need です to make sense. です is added only for politeness.
The mistake to avoid
きれい and 有名 end in い but are な-adjectives. They are the exceptions everyone trips on.
Examples
この本は新しいです。
この ほんは あたらしいです。
This book is new.
寒いですね。
さむいですね。
It's cold, isn't it.