Forgery is a white-collar crime that refers to the false making or material alteration of a legal instrument with the specific intent to defraud anyone. Tampering with a certain legal instrument may be forbidden by law in some jurisdictions but such an offense is not related to forgery unless the tampered legal instrument was used in the course of the crime to defraud another person or entity. Copies, studio replicas, reproductions are not considered forgeries, though they may become forgeries through knowing and willful misrepresentations. Forging money or currency is more called counterfeiting, but consumer goods may be counterfeits if they are not manufactured or produced by the designated manufacturer or producer given on the label or flagged by the trademark symbol. When the object forged is a record or document it is called a false document; this usage of "forgery" does not derive from metalwork done at a blacksmith's forge, but it has a parallel history. A sense of "to counterfeit" is in the Anglo-French verb forger, meaning "falsify".

A forgery is concerned with a produced or altered object. Where the prime concern of a forgery is less focused on the object itself – what it is worth or what it "proves" – than on a tacit statement of criticism, revealed by the reactions the object provokes in others the larger process is a hoax. In a hoax, a rumor or a genuine object planted in a concocted situation, may substitute for a forged physical object; the similar crime of fraud is the crime of deceiving another, including through the use of objects obtained through forgery. Forgery is one including identity theft. Forgery is one of the threats addressed by security engineering. In the 16th century, imitators of Albrecht Dürer's style of printmaking improved the market for their own prints by signing them "AD", making them forgeries. In the 20th century the art market made forgeries profitable. There are widespread forgeries of valued artists, such as drawings by Pablo Picasso, Paul Klee, Henri Matisse. A special case of double forgery is the forging of Vermeer's paintings by Han van Meegeren, in its turn the forging of Van Meegeren's work by his son Jacques van Meegeren.

In England and Wales and Northern Ireland, forgery is an offence under section 1 of the Forgery and Counterfeiting Act 1981, which provides: A person is guilty of forgery if he makes a false instrument, with the intention that he or another shall use it to induce somebody to accept it as genuine, by reason of so accepting it to do or not to do some act to his own or any other person’s prejudice. "Instrument" is defined by section 8, "makes" and "false" by section 9, "induce" and "prejudice" by section 10. Forgery is triable either way. A person guilty of forgery is liable, on conviction on indictment, to imprisonment for a term not exceeding ten years, or, on summary conviction, to imprisonment for a term not exceeding six months, or to a fine not exceeding the statutory maximum, or to both. For offences akin to forgery, see English criminal law#Forgery and cheating; the common law offence of forgery is abolished for all purposes not relating to offences committed before the commencement of the Forgery and Counterfeiting Act 1981.

Forgery is not an official offence under the law of Scotland, except in cases where statute provides otherwise. The Forgery of Foreign Bills Act 1803 was repealed in 2013. In the Republic of Ireland, forgery is an offence under section 25 of the Criminal Justice Act, 2001 which provides: A person is guilty of forgery if he or she makes a false instrument with the intention that it shall be used to induce another person to accept it as genuine and, by reason of so accepting it, to do some act, or to make some omission, to the prejudice of that person or any other person. A person guilty of forgery is liable, on conviction on indictment, to imprisonment for a term not exceeding ten years, or to a fine, or to both. Any offence at common law of forgery is abolished; the abolition of a common law offence of forgery does not affect proceedings for any such offence committed before its abolition. Except as regards offences committed before the commencement of the Criminal Justice Act, 2001 and except where the context otherwise requires, without prejudice to section 65 of that Act, references to forgery must be construed in accordance with the provisions of that Act.

Forgery is an offence under sections 367 and 368 of the Canadian Criminal Code. The offence is a hybrid offence, subject to a maximum prison sentence of: if tried summarily: 6 months if tried on indictment: 10 years Forgery is a crime in all jurisdictions within the United States, both state and federal. Most states, including California, describe forgery as occurring when a person alters a written document "with the intent to defraud, knowing that he or she has no authority to do so." The written document has to be an instrument of legal significance. Punishments for forgery vary widely. In California, forgery for an amount under $950 can result in misdemeanor charges and no jail time, while a forgery involving a loss of over $500,000 can result in three years in prison for the forgery plus a five-year "conduct enhancement" for the amount of the loss, yielding eight years in prison. In Connecticut, forgery in the Third Degree, a class B misdemeanor is punishable by up to 6 months in jail, a $1000 fine, probation.

As to the effect, in the United Kingdom, of a forged signature on a bill of exchange, see section 24 of the Bills of

Yu Dayou, courtesy name Zhifu, art name Xujiang, was a Chinese general and martial artist best known for countering the wokou pirates along China's southeastern coast during the reign of the Jiajing Emperor in the Ming dynasty. Yu Dayou was born in present-day Heshi Village, Luojiang District, Fujian, but his ancestral home was in present-day Huoqiu County, Lu'an, Anhui, he sat for the military version of the imperial examination in 1535 and obtained the position of a wujinshi. He was appointed as a guard in the imperial palace. In 1555, Yu Dayou, along with the Zhuang noblewoman, Wa Shi, led Ming forces to attack the wokou pirates who were raiding near Jiaxing and defeated about 2,000 of them. In the following year, he was promoted to garrison commander of Zhejiang and was ordered to eliminate the wokou threat, he led Ming forces to attack the wokou base in Zhoushan in northeastern Zhejiang. In 1562, Yu Dayou was reassigned to serve as the garrison commander of Fujian. In the following year, he joined Qi Jiguang and other Ming generals in attacking the wokou at Putian and seized back the city from the enemy.

By 1566, most of the wokou who had terrorised China's southeastern coast had been driven away. Yu Dayou was known for being an upright official; when he met representatives from the influential spy agency, Eastern Depot, he refused to provide bribes to them and ended up being framed on false charges and imprisoned. Although he was saved by Qi Jiguang and Hu Zongxian, he nonetheless felt disappointed with political corruption within the Ming government and died in frustration, he was posthumously honoured as "Left Chief Controller" and given the posthumous name "Wuxiang". His son Yu Zigao served as military governor of Fujian, he forced the Dutch to withdraw from Penghu Island to Taiwan in 1624, but was subjected to a series of massive raids in 1627 and 1628 by Zheng Zhilong, culminating in the sack of his base at Xiamen. Dayou Street in Liandu District, Zhejiang is named after Yu Dayou to celebrate his achievements in defeating the wokou. Yu Dayou's tomb in Luojiang District, Fujian has been designated by the Fujian provincial government as a Historical and Cultural Site Protected at the Provincial Level.

Yu Dayou was a martial artist who specialised in a style of weapon fighting called "Jingchu Changjian". He studied martial arts in Shaolin Monastery, wrote and compiled Zhengqi Tang Ji. In his book, there is a section called Jian Jing, which became a martial arts manual by itself. Around 1560, Yu Dayou travelled to Shaolin Monastery to observe the Shaolin monks' fighting techniques; as a result, he returned to the south along with two monks and Pucong. Over the next three years, he taught them the "Yu Family Staff", a set of staff movement techniques he created based on the "Jingchu Changjian" and "Yang Family Spear". Zongqing and Pucong returned to Shaolin Monastery and taught other monks what they had learned. Tang Hao, a 20th-century martial arts expert, traced the Shaolin staff style Wu Hu Lan to Yu Dayou's teachings. Shahar, Meir. "Ming-Period Evidence of Shaolin Martial Practice". Harvard Journal of Asiatic Studies. Harvard Journal of Asiatic Studies, Vol. 61, No. 2. 61: 359–413. Doi:10.2307/3558572.

ISSN 0073-0548. JSTOR 3558572. Zhang, Tingyu. History of Ming, Volume 212

Metalurgia Casal was the largest Portuguese motorcycle manufacturer, based in Aveiro. It was founded in 1953 and its first products included agricultural engines. Business leader João Casal met representatives of Zündapp at a trade fair in Hanover in the early 1960s, started to build mopeds with Zündapp engines. From 1966 he made his own engine, the Casal engine, a modified copy of the Zündapp, to be built in many variants; the first all-Casal model was the four speed 50 cc scooter Casal S170 Carina. Casal expanded the production to ordinary motorcycles; the first was called K181. In the early-1970s Casal began to export their products, for example to the UK, Netherlands and Sweden. Car production was planned, but not realised; as the increased purchasing power in their home country Portugal, their most important market, slowed down the sales of mopeds, bankruptcy was a fact in February 2000. In connection with this parts of the company's archives were destroyed. Today it operates as a Suzuki representative in Portugal.

Some Casals has survived in their home country Portugal, but for example in Sweden, where the Swedish type K190 is quite common with collectors. Casal build the Casal RZ 50, some of this models where chosen to be modified " bore out up to 92cc or use the 125cc barel port polished to achieve incredible performance. Motoplat ignicion and all the types of carburetors the best to use being the 32mm flat with bored jets, with lightned balanced crack and piston; the best exhaust was hand built by a local guy using his one bike as test bench, his bike would give a run to the Suzuki RGV 250 or some other 600cc 4 stroke bikes up to 180 km/h. In 1980 Jan Nijhuys took a 1/4 mile record with a Casal Sparta Plompen. Quarter mile was covered in record speed after 402m where 94.29 km/h. In 1981 the Dutch Jan Huberts bettered the 50cc speed record with a HuVo-Casal to 224 km/h. To become competitive, Casal made a partnership with the Dutch company HuVo; this joint venture made possible to score great results in road racing competitions.

Casal-HuVo joined World Grand Prix in 80cc class on 1984 and 1985 seasons. 50cc Road Racing History http://www.elsberg-tuning.dk/recordbikes.html Rebuilding a 1975 Casal K166 Moped http://david.szego.me/blog/?p=23 Casal on the Portuguese reference motorcycle brands database website "Motos de Portugal" http://motosdeportugal.com/en/brands/casal Robert M. Croucher, "The Observer Book of Motorcycles", London