[Affidavit]: Very often, a person makes an affidavit for evidence purpose e.g. in court proceedings or for proof of certain matters to the Consulate General. If the affidavit is intended to be used outside Hong Kong, the authority may require the maker to do it before a Notary Public.
An affidavit is a voluntary declaration of facts or oath, made by an individual. It is usually considered a stronger statement, since it is attested to in front of a notary public or someone else authorized to administer such an oath.
An affidavit often contains language like this:
I solemnly swear that the foregoing statements are true and correct to the best of my knowledge and belief.