です

1. Origins, structure, and basic meaning

• Structure: Add です after a noun or na-adjective stem to complete a judgment politely.
  • 会社員です, 静かです
• Basic usage: It explains a subject's identity, quality, location relationship, or similar attribute.
  • 父は会社員です。 politely states the father's occupation.

2. Common pitfalls and similar expressions

• Polite verb forms
  • Make a verb polite through a form such as 行きます. The form 行くです incorrectly adds です directly to a plain verb.
• Tense with i-adjectives
  • 高いです is also possible, but its past form changes the adjective to 高かったです. It does not follow the same pattern as the past noun predicate 学生でした.
• Distinct from existence
  • ここは学校です identifies this place as a school, whereas ここに学校があります says a school exists here. です cannot replace every verb of existence.