"A whitepaper is a persuasive, authoritative, in-depth report on a specific topic that presents a problem and provides a solution.
Marketers create whitepapers to educate their audience about a particular issue or explain and promote a particular methodology. They're advanced problem-solving guides. Typically, whitepapers require at least an email address for download (usually they require information more than that), making them great for capturing leads."
A whitepaper is NOT:
"A product pitch.
Although Investopedia, [see above], defines a whitepaper as 'an informational document issued by a company to promote or highlight the features of a solution, product, or service', be warned that overtly shilling your own stuff could turn off your readers. The goal of a whitepaper is to inform and persuade based on facts and evidence, not tell the world why your product is the best and they need to buy it now." [Investopedia seems to have backed off from this stance.]
from Hubspot