You use をもとに to say that you create, decide, or do something using a particular basis. The basis is the foundation, and what you do is built on it. It often appears in formal or written contexts, like reports, explanations, or announcements. A similar but more casual spoken form is をもとにして, which can be followed by a verb if needed (e.g., をもとにしている).

Think of it as 'with X as the basis' or 'drawing on X.' The source (the noun before をもとに) is what you rely on, and the result (what comes after) is what you make or conclude. It is neutral in tone, but more common in writing than in everyday chat.

Note that you cannot just attach it to a plain verb form. If you need to base something on an action, turn that action into a noun phrase first, like 調査の結果 (results of investigation) or データ (data).