content portion; body
Computing term referring to the main content area of a document, webpage, or data structure, as opposed to headers, footers, or metadata.
HTMLでは、内容部を専用のタグで囲むことが推奨されています。
In HTML, it is recommended to enclose the content portion with a dedicated tag.
このテンプレートでは、ヘッダーとフッターを
In this template, please edit only the content portion, excluding the header and footer.
コンテンツ is a broader term for content in general, including multimedia, whereas 内容部 specifically denotes the structural portion containing that content.
generic content portion
Compound of 内容 (ないよう, 'content') and 部 (ぶ, 'part' or 'section'). The term is a straightforward technical coinage.