What's the difference between a content header and a header?

Question

HttpRequestMessage

Has Content.Headers and Headers

Why is that? when I google Http protocol online, I don't see anyone mentioning a content header and a normal header, there are only "headers"

Answer 1

Unfortunately, the MSDN documentation for MVC, WebAPI and System.Net.Http are appaling. See HttpContentHeaders.ContentType Property:

Gets or sets {insert text here}.

Well-known content-specific headers are grouped under "content headers". It's just for convenience. There are headers like content-type, content-length, and so on, as seen in HttpContentHeaders Class:

• Public property Allow Gets {insert text here}.
• Public property ContentDisposition Gets or sets {insert text here}.
• Public property ContentEncoding Gets {insert text here}.
• Public property ContentLanguage Gets {insert text here}.
• Public property ContentLength Gets or sets {insert text here}.
• Public property ContentLocation Gets or sets {insert text here}.
• Public property ContentMD5 Gets or sets {insert text here}.
• Public property ContentRange Gets or sets {insert text here}.
• Public property ContentType Gets or sets {insert text here}.
• Public property Expires Gets or sets {insert text here}.
• Public property LastModified Gets or sets {insert text here}.