A style of Japanese speech/ writing characterized by sentences ending in 'desu' and verbs in the 'masu' form — the polite 'desu/masu' style.
小学生向けの教材は多くがです体で書かれている。
Many textbooks for elementary school students are written in the desu style.
ビジネスメールでは、基本的にです体で書くのが無難だ。
For business emails, it's generally safe to write in the desu/masu style.