Signature in the context of "Hanko (stamp)"

Huaya ("flower seal"; Chinese: 花押; pinyin: Huā Yā; Korean: 화압, romanized: Hwaap; Japanese: 花押, romanized: Kaō, Vietnamese: hoa áp, chữ Hán: 花押) are stylized signatures or marks used in East Asian cultures in place of a fully written signature. Originating from China, the huaya was historically used by prominent figures such as government officials, monks, artists, and craftsmen. The use of stamp seals gradually replaced the huaya, though they are still used occasionally in modern times by important people.

An affidavit (/ˌæfɪˈdeɪvɪt/ AF-ih-DAY-vit; Medieval Latin for "he has declared under oath") is a written statement voluntarily made by an affiant or deponent under an oath or affirmation which is administered by a person who is authorized to do so by law. Such a statement is witnessed as to the authenticity of the affiant's signature by a taker of oaths, such as a notary public or commissioner of oaths. An affidavit is a type of verified statement or showing, or containing a verification, meaning it is made under oath on penalty of perjury. It serves as evidence for its veracity and is required in court proceedings.

In law, non-repudiation is a situation where a statement's author cannot successfully dispute its authorship or the validity of an associated contract. The term is often seen in a legal setting when the authenticity of a signature is being challenged. In such an instance, the authenticity is being "repudiated".

For example, Mallory buys a cell phone for $100, writes a paper cheque as payment, and signs the cheque with a pen. Later, she finds that she can't afford it, and claims that the cheque is a forgery. The signature guarantees that only Mallory could have signed the cheque, and so Mallory's bank must pay the cheque. This is non-repudiation; Mallory cannot repudiate the cheque. In practice, pen-and-paper signatures are not hard to forge, but digital signatures can be very hard to break.

An X mark (also known as an ex mark or a cross mark or simply an X or ex or a cross) is either used to indicate the concept of negation (for example "no, this has not been verified", "no, that is not the correct answer" or "no, I do not agree"), or indicate affirmation (for example, in election ballot papers, legal documents, or maps as an x-marks-the-spot). When used to mean "no," its opposite is often considered to be the O mark used in Japan and Korea or the check mark (✓) used in the West. When used to mean "yes," it is often completely interchangeable with a check mark. In Japanese, the X mark (❌) is called "batsu" (ばつ) and can be expressed by someone by crossing their arms.

It is also used as a replacement for a signature for a person who is blind or illiterate and thus cannot write their name. Typically, the writing of an X used for this purpose must be witnessed to be valid.

An electronic signature, or e-signature, is data that is logically associated with other data and which is used by the signatory to sign the associated data. This type of signature has the same legal standing as a handwritten signature as long as it adheres to the requirements of the specific regulation under which it was created (e.g., eIDAS in the European Union, NIST-DSS in the USA or ZertES in Switzerland).

Electronic signatures are a legal concept distinct from digital signatures, a cryptographic mechanism often used to implement electronic signatures. While an electronic signature can be as simple as a name entered in an electronic document, digital signatures are increasingly used in e-commerce and in regulatory filings to implement electronic signatures in a cryptographically protected way. Standardization agencies like NIST or ETSI provide standards for their implementation (e.g., NIST-DSS, XAdES or PAdES). The concept itself is not new, with common law jurisdictions having recognized telegraph signatures as far back as the mid-19th century and faxed signatures since the 1980s.

Signature recognition is an example of behavioral biometrics that identifies a person based on their handwriting. It can be operated in two different ways:

Static: In this mode, users write their signature on paper, and after the writing is complete, it is digitized through an optical scanner or a camera to turn the signature image into bits. The biometric system then recognizes the signature analyzing its shape. This group is also known as "off-line".

In law, countersignature refers to a second signature onto a document. For example, a contract or other official document signed by the representative of a company may be countersigned by their supervisor to verify the authority of the representative. Also, a money order or other financial instrument may be signed once upon receipt, then signed again by the same person when presented for payment, as an indication that the bearer is the same person who originally received the item, and not a thief who has stolen the item before it could be carried to the place where it was to be presented.

An example in which a countersignature is needed is with British passport applications.

Signature forgery refers to the act of falsely replicating another person's signature.

An autograph is a person's own handwriting or signature. The word autograph comes from Ancient Greek (αὐτός, autós, "self" and γράφω, gráphō, "write"), and can mean more specifically:

• a manuscript written by the author of its content. In this meaning the term autograph can often be used interchangeably with holograph.
• a celebrity's handwritten signature. Autograph collecting is the activity of collecting such autographs.

A tughra (Ottoman Turkish: طغرا, romanized: ṭuġrā; Turkish: tuğra) is a calligraphic monogram, seal or signature of a sultan that was affixed to all official documents and correspondence. Inspired by the tamgha, it was also carved on his seal and stamped on the coins minted during his reign. Very elaborate decorated versions were created for important documents that were also works of art in the tradition of Ottoman illumination, such as the example of Suleiman the Magnificent in the gallery below.

The tughra was designed at the beginning of the sultan's reign and drawn by the court calligrapher or nişancı on written documents. The first tughra examples are from the 14th century.