A document or public instrument is a document issued or authorized by a competent public official or public notary and that attests to its contents by itself.[1]​.

In general, public documents are those issued by public officials in the exercise of their functions. In Spain, article 1216 of the Civil Code defines what is meant by a public document: "Document issued or authorized by a competent public official with the solemnities required by law."

In Colombia, according to the definition of the Code of Civil Procedure (article 251), a public document is one granted by a public official in the exercise of his position or with his intervention. It is called a public instrument when it consists of a writing authorized or signed by the respective official; It is called a public deed, when it is granted by a notary or whoever acts in his place and has been incorporated into the respective protocol. The private document is, by exclusion, any document that does not meet the requirements to be public. It is, therefore, an organic perspective, since the public nature of the document is determined by the person or body where it originates. The scope of production of the document - the producing subject and its quality - is what defines and determines, ultimately, its public nature. Consequently, the data contained in a public document, by its nature and except for the exceptions stipulated by law, are also public.

However, in Spanish Law, for procedural purposes, those listed in article 317 of the civil procedure law are also considered public documents:[2]​.

Sworn translations, that is, translations carried out or certified by an expert translator, are also considered public documents.

Article 1218 of the Civil Code of Spain regulates the evidentiary force of public documents.

Public documents provide proof even against third parties of the fact that motivates their granting and the date of this. They will also take evidence against the contracting parties and their assigns, regarding the statements that the former have made in them.